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Occupational noise induced hearing loss and engineered noise control : knowledge and perception in the… Nahid, Musarrat 2009

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Occupational Noise Induced Hearing Loss and Engineered Noise Control: Knowledge and Perception in the Food Products Manufacturing Industry in British Columbia by  MUSARRAT NAHID A THESIS SUBMITTED IN THE PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Occupational and Environmental Hygiene)  THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) August, 2009 ©Musarrat Nahid, 2009  Abstract Workplaces primarily rely on hearing protection devices (HPDs) for prevention of occupational noise induced hearing loss (NIHL). This study was initiated to investigate the potential barriers to the implementation of engineered noise control (ENC) which is considered to be the best prevention measure. The study investigated knowledge and perception about NIHL and ENC among decision-makers and workers in the food products manufacturing industry in British Columbia. We contacted company Health and Safety Departments. They were sent packages of questionnaires and return envelopes for distribution among specified subjects. Follow-up phone calls were made to increase participation. Analysis included descriptive statistics, nonparametric methods and simple and multiple logistic regressions. Twenty-two companies and 92 individuals participated (response rate 32.5%). Nearly two-third of the respondents were non-management. A similar proportion was involved in health and safety activities. The majority of the respondents perceived NIHL to be a big disadvantage and said that they would be bothered by it. Respondents were knowledgeable about the effects of noise exposure on health but had poor knowledge about harmful levels of noise, ENC and the limitations of HPDs. They considered HPDs, hearing tests and education to be more effective in preventing NIHL than ENC. Management showed poorer knowledge and lower perception than non-management. Those involved in health and safety performed slightly better than those who were not involved in such activities. Interventions should be undertaken to educate management about ENC options and limitations of HPDs. Regulatory agency should create special branches to help workplaces in choosing suitable ENC.  ii  Table of contents Abstract .................................................................................................................................................................. ii Table of contents ................................................................................................................................................... iii List of tables .......................................................................................................................................................... vi List of figures ...................................................................................................................................................... viii List of abbreviations ............................................................................................................................................. ix  1. Introduction ....................................................................................................................................................... 1 1.1 Occupational noise and hearing loss- the size of the problem ............................................................. 1 1.2 Noise induced hearing loss .................................................................................................................. 1 1.2.1Development of noise induced hearing loss ................................................................................ 1 1.2.2. The impacts of hearing loss on well-being ................................................................................ 2 1.3 Current interventions ........................................................................................................................... 3 1.4 Engineered noise controls .................................................................................................................... 4 1.4.1 Principles of engineered noise controls ...................................................................................... 4 1.4.2 Importance of engineered noise controls .................................................................................... 5 1.5 Current scenario regarding prevention of noise induced hearing loss ................................................................................................... 6 1.6 Research on barriers to the adoption of engineered noise control ..................................................................................................... 7 1.7 Importance of knowledge and perception ............................................................................................ 8 1.7.1 Knowledge of risk ....................................................................................................................... 8 1.7.2 Perception of risk ........................................................................................................................ 9 1.7.3 Knowledge of prevention measure ............................................................................................. 9 1.7.4 Perception of efficacy of prevention measure ........................................................................... 10 1.7.5 Importance of knowledge and perception in the context of health promotion model: the PRECEDE/PROCEED model ....................................................... 10 1.8 Research gap ...................................................................................................................................... 11 1.9 Study rationale ................................................................................................................................... 13 2. Research questions .......................................................................................................................................... 15 3. Methods ............................................................................................................................................................ 16 3.1 Ethics approval ................................................................................................................................ 16 3.2 Selection of companies ..................................................................................................................... 16 3.3 Study sample ..................................................................................................................................... 16 3.4 Recruitment and follow-up ............................................................................................................... 17 3.5 Questionnaire .................................................................................................................................... 18 3.5.1Questionnaire development ...................................................................................................... 18 3.5.2 Pretesting the questionnaire ..................................................................................................... 19 3.5.3 Questionnaire content ............................................................................................................. 20 3.5.4 Reliability of the questionnaire................................................................................................ 23 3.5.5 Delivery of the questionnaire .................................................................................................. 24 3.6 Data coding, error checking and management .................................................................................. 25 3.7 Data analysis ...................................................................................................................................... 27 3.7.1 Aggregate response .................................................................................................................. 27  iii  3.7.2 Response among subgroups ..................................................................................................... 27 3.7.3 Multivariable analyses ............................................................................................................. 28 3.7.3.1 Overview.................................................................................................................... 28 3.7.3.2 Knowledge of risk ...................................................................................................... 29 3.7.3.3 Perception of risk ....................................................................................................... 29 3.7.3.4 Perception of efficacy of engineered noise control .................................................... 30 4. Results ............................................................................................................................................................... 31 4.1 Overview .......................................................................................................................................... 31 4.2 Questionnaire reliability ................................................................................................................... 31 4.3 Recruitment summary and response rate .......................................................................................... 31 4.4 Information on the participant companies ........................................................................................ 32 4.5 Demographics ................................................................................................................................... 33 4.6 Aggregate response ........................................................................................................................... 35 4.6.1 Knowledge of risk ................................................................................................................... 35 4.6.2 Perception of risk ..................................................................................................................... 37 4.6.3 Knowledge of engineered noise control................................................................................... 42 4.6.4 Perception of efficacy of engineered noise control .................................................................. 43 4.6.5 Other perceptions about engineered noise control ................................................................... 45 4.6.6 Other ........................................................................................................................................ 45 4.7 Response among subgroups .............................................................................................................. 46 4.7.1 Knowledge of risk .................................................................................................................... 46 4.7.2 Perception of risk ..................................................................................................................... 48 4.7.3 Knowledge of engineered noise control................................................................................... 51 4.7.4 Perception of efficacy of engineered noise control .................................................................. 53 4.7.5 Other ........................................................................................................................................ 53 4.8 Multivariable analyses ....................................................................................................................... 54 4.8.1 Association between independent variables.............................................................................. 54 4.8.2 Knowledge of risk ..................................................................................................................... 54 4.8.2.1 Univariate analyses ..................................................................................................... 54 4.8.2.2 Multivariate analyses .................................................................................................. 55 4.8.3 Perception of risk ...................................................................................................................... 56 4.8.3.1 Univariate analyses ..................................................................................................... 56 4.8.3.2 Multivariate analyses .................................................................................................. 56 4.8.4 Perception of efficacy of engineered noise control ................................................................... 57 4.8.4.1 Univariate analyses ..................................................................................................... 57 4.8.4.2 Multivariate analyses .................................................................................................. 58 4.8.5 Summary .................................................................................................................................. 58 5. Discussions........................................................................................................................................................ 59 5.1 Overview .......................................................................................................................................... 59 5.2 Answering the research questions .................................................................................................... 59 5.2.1 Knowledge of risk ................................................................................................................... 59 5.2.2 Perception of risk .................................................................................................................... 63 5.2.3 Knowledge of engineered noise control .................................................................................. 66 5.2.4 Perception of efficacy of engineered noise control .................................................................. 68 5.3 Recommendation .............................................................................................................................. 70 5.4 Future research ................................................................................................................................. 74 5.5 Strengths and limitations .................................................................................................................. 74 6. Conclusions ...................................................................................................................................................... 77 References ............................................................................................................................................................ 78  iv  Appendices ........................................................................................................................................................... 86 A. Ethics approval ................................................................................................................................... 86 B. Invitation letter ................................................................................................................................... 87 C. Instruction sheet ................................................................................................................................. 89 D. Request for redistribution of the questionnaires ................................................................................. 90 E. Questionnaire ...................................................................................................................................... 92 F. Classification of questions ................................................................................................................ 112 G. Information letter .............................................................................................................................. 114  v  List of tables Table 1: Description of PRECEDE/PROCEED model ......................................................................................... 11 Table 2: Classification of questions based on contents ........................................................................................ 22 Table 3: List of subgroups .................................................................................................................................... 25 Table 4: Risk perception statements used for creating the dependent variable for MLR analyses of perception of risk ......................................................................... 30 Table 5: Demographical characteristics of the respondents .................................................................................. 33 Table 6: Characteristics of respondents in the subgroups (based on job responsibility and involvement in health and safety activities) ........................................................... 34 Table 7: Knowledge of risk (Likert scale questions) ............................................................................................ 36 Table 8: Knowledge of risk (multiple choice questions) ...................................................................................... 36 Table 9: Median and mode values of ranks for some occupational health problems ............................................ 39 Table10: Median and mode values of ranks for some chronic diseases ............................................................... 40 Table 11: Perception of risk among the respondents ........................................................................................... 41 Table 12: Knowledge of information sources of ENC ......................................................................................... 42 Table 13: Median and mode values of ratings assigned by the respondents to different prevention measures used to prevent NIHL ...................................................................................... 44 Table 14: Perception of feasibility and other benefits of ENC ............................................................................. 45 Table15: Percentage of respondents in the subgroups aware about the following facts about noise exposure and hearing loss .................................................................................... 47 Table16: Percentage of respondents in the subgroups assigning “rank 1 (most concerning)” to hearing loss ................................................................... 49 Table 17: Percentage of respondents in the subgroups showing high risk perception regarding the consequences of NIHL on life .................................................................................. 50 Table 18: Perception among subgroups (%) about a worker’s chance of developing NIHL and their own hearing ......................................................................................... 51 Table 19: Percentage of respondents in the subgroups aware of BC’s OHS regulations ...................................... 52 Table 20: Knowledge of information sources of ENC among respondents (%) in different subgroups .............. 52 Table 21: Percentage of respondents in the subgroups considering “ENC” as “highly effective” measure in preventing hearing loss ............................................................................. 53 Table 22: Results of simple logistic regression analyses between knowledge of risk and each independent variable  vi  (total number of respondents with good level of knowledge = 46) ........................... 55 Table 23: Results of MLR analyses of knowledge of risk .................................................................................... 55 Table 24: Results of simple logistic regression analyses between perception of risk and each independent variable (total number of respondents with high risk perception=74) ................................... 56 Table 25: Results of MLR analyses of perception of risk ..................................................................................... 57 Table 26: Results of simple logistic regression analyses between perception of efficacy of ENC and each independent variable (total number of respondents with high perception of efficacy of ENC=30) ........................................................................ 57 Table 27: Results of MLR analyses of perception of efficacy of ENC ................................................................. 58  vii  List of figures Figure1: Ranks assigned by the respondents to some occupational health problems indicating how serious/concerning these were to them (with “1” being the most serious/concerning one and “5” being the least serious/concerning one) ....................................................... 38 Figure 2: Level of concern expressed by respondents if they were diagnosed with certain chronic diseases ........................................................................................... 40 Figure 3: Ratings assigned by respondents to different prevention measures in terms of their effectiveness in preventing NIHL .................................................................................................... 44  viii  List of abbreviations AT  Audiometric tests  BCMD  British Columbia Manufacturers’ directory  ENC  Engineered noise control  HCP  Hearing conservation program  HPD  Hearing protection devices  HS  Health and safety  JHSC  Joint health and safety committee  NIHL  Noise induced hearing loss  OHS  Occupational health and safety  ON  Occupational noise  RSI  Repetitive Strain Injury  ix  1. Introduction 1.1Occupational noise and hearing loss: the size of the problem Occupational noise is considered to be a major cause of adult-onset hearing loss worldwide (1). Workers across the world continue to be at risk of hearing loss due to the presence of a high level of noise at their workplaces (2). In USA, more than 30 million workers (almost 1 in 10) are exposed to unsafe noise levels on the job (3) and occupational noise is considered to be the most prevalent occupational hazard in that country (4). In Europe, about 35 million people are exposed to detrimental noise levels (> 85 dB-A) in industrial plants (5). In the Canadian province of British Columbia (BC), one fourth of all workers are exposed to high level of noise capable of causing hearing loss (6). Noise induced hearing loss is recognized to be a leading occupational health problem in the developed societies. Between 7.4 and 10 million workers in the USA suffer from noise induced hearing loss (NIHL) (7). The US National Institute of Occupational Health and Safety (NIOSH) ranks noise-induced hearing loss as one of the top 10 work-related problems in their country (8). In British Columbia, there appears to be an upward trend in the number of workers’ compensation claims associated with hearing loss over the years despite the presence of the Hearing Conservation Program (HCP) in the regulation for the last three decades (9).  1.2 Noise induced hearing loss 1.2.1 Development of noise induced hearing loss Noise induced hearing loss develops almost insidiously (10) over a period of 10-20 years (5). By the time it is noticeable, it may have reached a well advanced stage of disability (10). NIHL typically involves the frequency range (pitch) of human voices, and thus verbal communication is affected (1). When a person is exposed to a high level of noise, temporary hearing loss (temporary threshold shift-TTS) may occur (11). With the complete cessation of noise exposure, the auditory threshold returns to normal within a few hours. But if the noise exposure continues for long periods and/or periods of recovery are reduced, permanent hearing loss or permanent threshold shift (PTS) occurs. It becomes noticeable when the person faces difficulty in carrying out verbal communication in regular activities. PTS is irreversible (11). 1  Hearing aids may provide improved understanding of speech although they cannot replace normal hearing; moreover, these instruments may also make background noise sharper and more distracting (12). The first signs of hearing loss can be detected in the audiogram, which is usually a dip or notch in the audiogram maximal at 4 kHz (10). The notch broadens with increasing exposure, and may eventually become indistinguishable from the changes of aging (presbycusis) when the hearing shows a gradual deterioration at the high frequencies (10). The pure-tone average and the average hearing thresholds at 4 kHz may significantly increase with an increasing noise exposure level (13). The chance of incurring a hearing disability for a person who has 30 years of work experience in a 90-dBA sustained occupational noise exposure is 23 percent (assuming that working life begins at the age of 20) (14).  1.2.2 The impacts of hearing loss on well-being NIHL can have a significant negative impact on the quality of life (15) (16). Hearing loss not only interferes with an individual’s working life but can also restrict social activities and create problems in his/her personal life (16). It may be a risk in an industrial work setting because of the inability to detect a warning signal or the localization of sound sources (16). In many cases, sufferers may try to conceal their hearing impairment for fear of being stigmatized by co-workers who, due to a lack of awareness about occupational hearing loss, may mistakenly assume the problem to be associated with the natural aging process or a biological defect (16). Hearing loss may be greeted with jokes by some co-workers (16). The affected person may try to withdraw himself from social gatherings (17) (16). Hearing loss may result in misunderstanding, reduced ability to interact freely with significant others and may be an obstacle in obtaining intimacy (17). Activities which were once enjoyed such as attending meetings, playing cards, watching television, going shopping, listening to music, going to parties, and talking over the telephone may not be enjoyable. Sometimes the affected persons may inappropriately respond to questions, or comments due to misunderstanding or misinterpretation of spoken messages; however, once they realize that they have showed such behaviour, this realization, in turn, may result in fear of appearing unintelligent and having diminished self esteem. A sense of isolation and incompetence may be present (17). Hearing impairment may also lead to significant problems in family life due to communication difficulties (16). As Smith et al. put it: “Family 2  members often do not understand the impact of the hearing loss, nor do they have techniques to deal with the problems associated with hearing impairment. Family members and other hearing people may respond to the deaf person by becoming impatient, or angry , by excluding the person from discussions and decision-making, by talking about him/her in his/her presence, by withholding information and by neglecting to make accommodations for the hearing loss” (17). In addition to NIHL, noise exposure has been associated with same non-auditory effects, such as sleep disturbance (18)(15), hypertension and ischemic heart diseases (18); chronic noise exposure has been found to be associated with the risk of myocardial infarctions (19). This nonauditory effect of noise exposure may be of high public health significance since cardiovascular disease is responsible for over 30% of the worldwide mortality (19). Noise can also cause annoyance (18) (15) and affect performance (18).  1.3 Current interventions In BC, as in other Canadian and US jurisdictions, the current intervention to prevent NIHL is the Hearing Conservation Program (HCP). The current regulatory limits for noise exposure are a) 85dBA Lex daily noise exposure level, and/or (b) 140 dBC peak sound level. If noise in the workplace exceeds either of the noise exposure limits, the employer must develop and implement an effective noise control and hearing conservation program (20). The components of the program are: 1. Noise measurement, 2. Education and training, 3. Engineered noise control (ENC), 4. Hearing protection, 5. Posting of noise hazard areas, 6. Hearing tests and 7. Annual program review. In the regulations, ENC has been given much priority over other prevention measures, such as, hearing protection devices (HPDs). In fact, it is mentioned as the first option to be investigated when the noise exposure exceeds the regulatory limits. Some sections of the noise regulations (21) are mentioned below to assist the reader in understanding the weight given to ENC by the regulations: “If a worker is exposed to noise above a noise exposure limit, the employer must (a) Investigate options for engineered noise control, and (b) When practicable, implement one or more of those options to reduce noise exposure of workers to or below the exposure limits. If it is not practicable to reduce noise levels to or below noise exposure limits, the employer must 3  (a) Reduce noise exposure to the lowest level practicable, (b) Post warning signs in the noise hazard areas, (c) Give to affected workers hearing protection.”  1.4 Engineered noise control 1.4.1 Principles of engineered noise control With engineered noise controls (ENCs), noise can be reduced at the source, along the propagation pathway or the receiver of sound i.e. worker. Examples of noise reduction at those 3 stages are given below: At the source (22)(23): Isolation of noisy machinery by acoustic enclosures and vibration isolators. Engineering acoustic enclosure design consists of structurally controlling all noise paths at the source. Commercially available materials designed to reduce structural-borne noise can be quite effective as an engineering control, particularly, where low frequency noise is a problem. Vibration isolators prevent noise from being transmitted through the base of the equipment, and through conduit, piping, ductwork and other devices which may be rigidly connected to the noise source. In the pathway (22)(23): Using acoustic partitions or barriers to block the transmission of noise from source to receiver; applying sound absorbing materials on walls, floors and ceilings of rooms; using baffles on the ceiling, etc. In factory buildings with hard or reflective surfaces, noise tends to reverberate, reflect and build-up throughout the plant; noise levels in such instances can often be reduced effectively by the addition of sound absorptive elements. Noise apparently builds up because it decays very slowly and with a continuous noise source, there will be no apparent decay at all. Apparent build-up can be reduced by lining surfaces with sound absorbing material. At the receiver (14) (6): providing a control room (actually an acoustic enclosure) for workers when it is not feasible to isolate the noisy machine.  4  1.4.2 Importance of engineered noise control The best way to prevent occupational noise induced hearing loss for a worker is the elimination or reduction of noise; in this context, engineered noise controls (ENCs) are the preferred solutions (24) (20). Similar opinion has been expressed by other experts- the majority of the global burden of NIHL can be minimized by the use of engineering controls to reduce the generation of noise at its source (1). The World Health Organization (WHO) Program for Prevention of Deafness and Hearing Impairment (PDH) also recommends ENCs to reduce noise at source as a means of prevention of NIHL (25). ENCs have been found to yield significant reductions in noise level. For example, Lehigh Portland Cement Company installed numerous types of noise-attenuating engineering controls at its largest plant in Union Bridge, Maryland, USA (23); noise levels reduced dramatically and the possibility of employee overexposure to noise was reduced greatly in many locations within the plant and eliminated completely in others. In Singapore, several companies were able to reduce noise levels by implementing noise control measures; some of which were relatively inexpensive and creative. The reduction in the number of occupational NIHL cases over the years had been attributed to companies’ adoption of ENCs (26). Reduction of noise level by a small amount, such as 3 dB, can greatly reduce the existing level of risk of hearing loss. It is hypothesized that the extent of hearing loss is proportional to a function of sound energy received (sound energy is a product of noise level and exposure duration) (8). A 3-dB increase or decrease represents a doubling or halving of the sound energy (this is known as equal energy hypothesis or 3-dB exchange rate) (27) and thus, doubling, or halving of the risk. With ENCs, such as barriers, it is possible to reduce noise by as much as 20 dBA (28). The reduction or elimination of noise would eliminate the need for HPDs, audiometric testing and other parts of HCPs (20). ENCs can result in a quieter environment, allowing employees to work comfortably and lowering the risk of NIHL and the non-auditory effects of noise exposure. Engineering controls should be considered as the primary method for protecting workers' hearing, with administrative measures and personal protective equipment only as secondary controls (23)(20). 5  1.5 Current scenario regarding prevention of noise induced hearing loss There is no conclusive evidence in the literature on whether current intervention i.e. the HCP is effective in preventing NIHL (29). However, some researchers argue that HCPs are not effective enough to conserve workers’ hearing (7). It appears that the number of NIHL cases is not diminishing despite the presence of HCPs (15). This appears to be true in BC as well (9). Similar conclusion applies to other parts of the world, for example US and Poland. NIHL is still among the top ten occupational diseases in the US even though HCPs have been in effect since 1972 (7). Despite progress being made in improving hearing conservation programs (both the technical and medical), occupational NIHL still remains a common and costly cause of disability in Poland (5). High number of NIHL cases, described above, may be attributed to the presence of high level of noise at workplaces. This seems to be a realistic reason since a research in the Washington State involving an evaluation of 10 companies in an industry with a high rate of hearing loss claims revealed that noise levels routinely exceeded 85 dBA (30). Although ENC should be viewed as the most preferred prevention option, literature suggests that this may not be the case. Noise control was of low or no priority in small and medium sized companies studied in Washington State, USA, although workers’ compensation claims for hearing loss was high in those companies (31). In another study involving 10 companies with high rates of NIHL, it was found out that only one company planned any new engineered noise controls (30). Although ENCs are considered to be the best means to prevent NIHL, and HPDs are recommended as secondary means (20), it appears that HPDs are the top choice for prevention of NIHL in workplaces; several studies support this observation (32)(33)(31). However, HPDs have a number of limitations. Workers’ hearing preservation cannot be guaranteed unless HPDs are well fitted and used all the time (34). Other researchers expressed similar opinions-inadequate protector fit may strongly influence the resulting sound attenuation (35); moreover, the effectiveness of HPDs greatly reduces if it is not worn 100% of the time (36)(37). The effectiveness of HPDs is highly variable in terms of the predicted and actual protection they provide. HPDs with higher predicted protection but less comfort were shown to be less effective than those with lower predicted protection but more comfort (36). There is a considerable amount of discomfort associated with HPD-use (32)(38)(31)(4). This discomfort 6  may arise from pressure on the outer ear, irritation of the ear canal lining, and perspiration (38). Verbal communication (32)(33)(4) and the detection of warning signals (32)(33) may become problematic with the use of HPDs. Moreover, HPDs may also be incompatible with gears and other personal protective equipments (32). These limitations are often overlooked while prescribing these to workers (32). Underuse of HPDs is suggested as one probable cause of high rates of NIHL (31) and the above limitations may explain the underuse of HPD by workers. The intermittent use of HPD, in turn, reduces the effectiveness of HPD.  1.6 Research on barriers to the adoption of engineered noise control Research done on identifying the probable barriers to the adoption of ENCs in workplaces is scant. A literature search was carried out in PubMed, Web of Science and Google Scholar databases using relevant search terms. Examples of search terms used in Pubmed and Google Scholar were are: “barriers to implementation of noise control,” “decision making process, engineered noise control”, “factors influencing implementation of noise control”, “why noise control is not implemented ?” “implementation of noise control in workplaces”, “noise control in workplaces”. Similar terms were used in Web of Science: “noise control AND barriers”, “noise AND reduction AND workplace”, “noise control AND decision making” etc. However, the literature search produced only a few relevant studies. A study (n=48 organizations in the heavy and light engineering, 'high tech', agriculture, foundries, metal fabrication, manufacturing, wool and textiles, oil and petrochemical industries, and local authorities in the United Kingdom; method: audits of HCP, interviews and questionnaires), focused on the individual and organizational factors affecting attitudes towards noise induced hearing loss (NIHL), revealed some information on engineered noise control (33). This study reported that the managers perceived ENC to be costly and complex. However, there was little evidence that the managers thoroughly investigated noise control measures. They expressed the need for better information on ENCs. Another study (n=4 workplaces: 2 sawmills and 2 machine shops in Finland; method: workplace inspection and discussion with safety personnel and workers) reported that a lack of knowledge of easy means to reduce noise was one of the reasons for not implementing ENCs in workplaces (39); it suggested that the best way to promote a noise control program was to give information and example of such programs. Thus, it is apparent that a lack 7  of knowledge (information on ENCs) may be a barrier to the implementation of ENCs. An article ( based on the opinion of an individual researcher) on control of risks due to occupational noise described step by step procedures for companies to minimize the risks of noise exposure to workers (40); however it did not shed any light on barriers to the adoption of ENCs. A pilot study (n=8 organizations in the food and beverage industry in BC; method: HCP audit, interviews), focused on identifying barriers to the adoption of ENCs in workplaces (41), identified several factors that may influence the decisions to implement ENCs in workplaces. These were knowledge and perception of risk, expert knowledge (e.g. knowledge of prevention measure, technical skill), corporate safety culture (e.g. avenue for worker participation in health and safety, management’s preoccupations and priorities), socio-economic and cultural factors (e.g. job insecurity which might prohibit workers’ from voicing concern), regulatory pressure and technological context (e.g. enough information about noise emission on equipment to help the management make informed decision while purchasing). This pilot study identified that organizational decision making was a complex process in which numerous human and organizational factors came into play. This study revealed that management taking action about any hazard largely depended on workers identifying a problem and bringing it to the management’s attention. The management then prioritized the hazards and made decisions. However, the decision making largely depended on how noise was viewed by both the management and workers and the management’s knowledge and perception about the efficacy of control measures. Therefore, among all the probable barriers, the following human factors appeared to have potential to influence the decision-making process regarding the implementation of ENC in workplaces: 1) knowledge and perception of risk and; 2) knowledge and perception of efficacy of prevention measure.  1.7 Importance of knowledge and perception 1.7.1 Knowledge of risk A lack of knowledge is identified as one of the barriers to change (42). Knowledge about occupational hazards is suggested to be a predictor of preventive behaviour at work (37)(43). Providing knowledge about risk (such as, toxicity of lead) to workplace stakeholders (workers (44)(45)and managers (45)) through educational intervention was found to be effective in 8  reducing lead poisoning among workers. Other studies also reported similar findings. A review published on a number of studies found that knowledge of AIDS, in general, was correlated with AIDS-preventive behavior (46). It is suggested that knowledge of risk (means of AIDS transmission) may be one of the necessary pre-requisites for risk-reduction behavior (46). In an intervention study (47), designed to increase participants’ knowledge of risk regarding cardiovascular diseases, it was found that knowledge of risk was associated with change in riskbehaviour, which, in turn, resulted in physiologic changes in risk for cardiovascular diseases.  1.7.2 Perception of risk Although knowledge is a necessary factor, it is not a sufficient reason to change individual or collective behaviour. Motivation to change is dictated by a combination of factors (48). Effective behavioural change is facilitated by greater knowledge, experience, and personal risk perception (49). Risk perception plays a significant role as a predictor of workers’ protective behaviour, such as, use of HPDs (50) (51)(34). A study on farmers’ use of protective equipment regarding noise, sun, dust, pesticides, and tractors found that risk perception was strongly associated with protective behaviour (52). Perceived risk of diseases (e.g. skin cancer) is a motivating factor to change behaviour. Perceived severity and perceived vulnerability and benefits are likely to motivate individuals to take preventive action (53). For example, people are willing to pay more for products reducing the risk of skin cancer when they perceive a high level of risk (54).These findings provide insights as NIHL is a chronic disease like skin cancer. Risk of getting skin cancer could make people refrain from doing harmful activities such as sunbathing (55).  1.7.3 Knowledge of prevention measures It is suggested that risk-reduction behaviour is a result of the information people have about prevention measures (46). This may well be true regarding the problem surrounding the adoption of ENCs. Research suggest that a lack of information regarding easy methods of reducing noise could hinder the realization of noise control programs in small and medium sized companies, especially in small companies which may need the assistance of noise experts to plan and realize a noise control program (39). Information and examples of noise control programs could 9  encourage its uptake in workplaces (39). In one study involving a questionnaire survey of 48 organizations and detailed case studies of 10 organizations, it was found that the management of most of the workplaces felt that information and practical guidance about ENC were inadequate (33). Other studies also stressed the importance of knowledge of prevention measure. Two studies on occupational lead exposure found that providing knowledge about prevention (how to protect workers from lead exposure) to workplace stakeholders (workers (45) (44)and managers (44)) induced behaviour changes among workers which reduced the risk of lead poisoning.  1.7.4 Perception of efficacy of prevention measures Perception of efficacy of prevention measures may also be important. Perceived ineffectiveness of the flu vaccine by health care workers was identified as one of the barriers to its adoption (56). Perceived effectiveness of the flu vaccine is also considered to be one of the reasons for its uptake by adults (57). One of the reasons behind choosing a particular birth control measure by women was found to be perception of effectiveness of that measure (58). Thus, perception of efficacy of a particular prevention measure may be an important factor to influence people’s decision about adopting that measure.  1.7.5 Importance of knowledge and perception in the context of health promotion model: the PRECEDE/PROCEED model Health promotion has emerged as an important tool in combating leading causes of death (48). Green’s PRECEDE/PROCEED model for health promotion planning has been proved to be a successful model for health promotion in a wide variety of situations (48). It has also been shown to be an effective tool in designing an occupational health and safety intervention1 (48)(59). The PRECEDE stage is the diagnostic or needs assessment stage and has 5 phases: phases 6-9 belong to the PROCEED aspect of the model and deal with the implementation and evaluation of the intervention (59). Table 1 summarizes the different phases of this model.  1  PRECEDE stands for predisposing reinforcing and enabling constructs for educational diagnosis and intervention; PROCEED stands for policy regulatory and organizational constructs in educational and environmental development  10  The PRECEDE framework helps the planner to shortlist potential factors out of a large number factors that shape health status, as the target for intervention for improving health (48). These factors are interrelated and can be categorized into three groups: predisposing, enabling and reinforcing factors. As put by Green, “Any given behavior can be explained as a function of the collective influence of these three types of factors.” Predisposing factors mainly belong to the psychological realm and are defined as factors facilitating or impeding motivation to change. These are knowledge, attitudes, beliefs, values and perceptions2 (48). Thus, from the above discussion, it is apparent that knowledge and perception are important factors for improving health conditions. Table 1: Description of PRECEDE/PROCEED model Phase 1. Social diagnosis 2.Epidemiological diagnosis  3. Behavioural and environmental diagnosis 4. Educational and organizational diagnosis 5. Administrative and policy diagnosis 6-9. Implementation and evaluation of the interventions  Description Assessment of quality of life concerns of the community in question Identification of specific health goals or problems that may contribute to the social goals or problems identified in phase 1. This is followed by a review of epidemiological and medical data, information generated through appropriate investigation. Moreover the size of the problem is also figured out to prioritize which health problem needs much attention Identification of the specific health related behavioural and environmental factors linked to the health problem/goal in phase 2 Identification of a series of interdependent factors that influence the expected behavioural and environmental change selected in phase 3. These factors are called predisposing, reinforcing and enabling factors Assessment of organizational resources, policies and capabilities to support planned activities or interventions Implementation of the intervention, process evaluation, impact evaluation and outcome evaluation.  1.8 Research gap Having described the occupational NIHL problem worldwide and the consequent diminished quality of life experienced by workers (low self-esteem, difficulty in maintaining  2  Enabling factors are often conditions of living within the environment that facilitate the desired change and are mainly created by societal forces or systems; examples being skills and resources. Reinforcing factors are the rewards or feedback received from others and social support after the change occurs  11  conversation and carrying out regular activities), other studies(16) (15) (17) have essentially shed some light on phase 1 of the Precede/Proceed model. Phase 2 has also been investigated by other studies which identified occupational NIHL as a contributor towards those concerns mentioned above (16) (15) (17) and studies which defined the size of the problem (i.e. how many people are affected) (1) (3) (4) (7) (8) (6). Environmental factors in the third phase are external to an individual, which can be changed to facilitate the health or quality of life of the person affected. Often these are beyond the control of the individuals-these factors may be organizational, economic or factors in the physical environment. Phase 3 has also been investigated by other studies (5) (41) which suggested reduction of noise through noise control solutions (i.e. ENC) as a preventive action. Workers’ health is not entirely dependent on workers themselves; workers seldom have any voice in the decision to create a working environment where their hazards appear (60). It is the firms that make major decisions about what to produce and how to produce it (60). Availability and effectiveness of hazard control measures depend on employers (59). Other researchers expressed similar opinions—much responsibility regarding occupational illness and injury prevention lies on line and senior managers (61). Top management involvement in safety was found to be associated with lower occupational accident rates (62). Thus, implementation of ENCs in workplaces, suggested in phase 3, can only come through these people’s approval of and support for ENCs. However, the role of joint health and safety committee (JHSC) members is also critical in the prevention of occupational diseases and injury since they are responsible for identifying occupational health and safety (OHS) problems and providing recommendations to employers (63). Thus, both the management and JHSC can be considered as decision makers regarding implementation of ENCs in workplaces. However, to initiate and facilitate the maintenance of that behaviour (i.e. adoption of ENCs) of the decision makers, the predisposing, enabling and reinforcing factors (of phase 4) must be investigated. Then key factors should be sorted out to target interventions. There is an order in how these 3 types of factors come into play to bring about a change in behaviour (48). The first step is to facilitate the motivation to change; motivation is influenced by predisposing factors. Then the deployment of enabling factors is needed to perform the required behaviour. After the occurrence of the behaviour, it should be strengthened by the reinforcing factors. Thus, 12  it is apparent that, the first step regarding phase 4, should be to investigate the predisposing factors such as knowledge and perception of decision makers. A literature search was carried out in Pubmed, Web of Science and Google Scholar using several combinations of the following keywords: risk perception/ knowledge, occupational noise/NIHL, decision makers/ managers/health and safety committee. In the literature, there are a few studies which reported findings on knowledge (64)(65) (34)and perception (34)(66,67) (24) (68) of risk about NIHL. However, these studies involved only workers- not the decision makers. Research involving decision makers and their knowledge and perception of efficacy regarding ENCs is almost non-existent. A literature search using combinations of the following keywords revealed no relevant studies: knowledge/perception of efficacy, noise control/ENC, decision makers/ managers/health and safety committee. Only one study (33) reported management’s perception about ENCs (cost and complexity); however, this study did not investigate management’s knowledge and perception of efficacy of ENCs in preventing NIHL. Thus, there is a need for research on 1) knowledge and perception of risk of NIHL and 2) knowledge and perception of efficacy of ENC in preventing NIHL involving decision makers.  1.9 Study rationale NIHL is a health problem that diminishes the quality of life of workers and hinders their ability to work. Moreover, the number of NIHL claims is rising and consequently, the cost of hearing loss claims will also rise. The best way to prevent NIHL is the elimination or, reduction of noise in workplaces. Engineered noise controls (ENCs) hold the best promise in this regard. According to noise regulations, the ENC option must be investigated as part of “Noise control and Hearing Conservation Program”. However, this option is not followed by the majority of workplaces whereas HPDs seem to dominate workplace-efforts in preventing NIHL. After long-term existence of HCPs, both in the regulations and in workplaces, the situation still has not improved. Thus, it is necessary to find out other ways to change this situation. Health promotion principles, such as, Green’s PRECEDE/PROCEED model may offer an effective solution to this problem since it has been found to be successful in dealing with a variety of situations including occupational health problems. Important aspects in this concept are knowledge and perception which are suggested to influence people’s motivation to change. 13  Research also suggested that knowledge and perception about risks (regarding NIHL) and prevention measures (ENCs) were barriers to workplaces’ uptake of ENCs. According to PRECEDE/PROCEED model, these factors should be the first foci of investigation when health promotion approach is considered for a particular health problem. However, little research has been done, in the context of NIHL prevention (through ENCs), to investigate the state of these important factors among the workplace decision-makers. This study was initiated to partially fill in this research gap. The research questions of this study are described in the next page.  14  2. Research questions 1. What is the level of knowledge and perception of risk regarding occupational noise exposure and NIHL among decision makers and workers in workplaces? Do subgroups of respondents differ in their knowledge and perception? 2. What is the level of knowledge among decision makers and workers in workplaces regarding ENCs? What is their perception of ENCs’ efficacy to prevent NIHL? Workers, in addition to decision makers, were included in this study since the pilot study (41) revealed that change in the workplace was highly dependent on workers’ knowledge and perception as well. The pilot study identified that the management relied on workers identifying and reporting hazards and offering potential solutions to them. “Knowledge of risk” was evaluated using questions about knowledge of the level of noise that can damage hearing, temporary loss of hearing and tinnitus due to short duration of exposure to noise, an early sign of NIHL, non-auditory effects of noise exposure, other causes of hearing loss, and limitations of HPDs (tightness of fit, protection lost due to not wearing HPDs for the entire shift); moreover, questions were also formulated to investigate the respondents’ awareness about loud noise (whether it can damage hearing) and slow pace and insidious nature of NIHL development. “Risk perception” was evaluated using questions about respondents’ level of concern for NIHL, perception of impacts of NIHL on life (difficulty in conversation, loss of quality of life; whether they considered it a handicap, or a troublesome attribute; whether NIHL may be viewed with contempt by others), and the chance of incurring NIHL at their workplaces. With respect to “knowledge of ENC”, we were interested in knowing whether subjects were aware of ENC (presence in the regulation), whether they were able to provide examples of ENCs and knew where to find information on ENCs. Regarding “perception of efficacy of ENC”, we were interested in knowing how effective they thought ENCs were in preventing NIHL compared to other commonly used prevention measures.  15  3. Method This study employed a questionnaire survey and statistical analysis (descriptive statistics, non-parametric methods and multivariable analyses).  3.1 Ethics approval All the requirements set out by the Behavioural Research Ethics Board (BREB) of UBC were fulfilled. The approval letter is attached in Appendix A.  3.2 Selection of companies The target sector was the food product manufacturing industry (WorkSafeBC industry sector: manufacturing; sub-sector: food and beverage products; classification unit 711001 to 711022). This industry is identified as one of the high-risk categories for occupational NIHL (69). WorkSafeBC’s statistics for 2005 show that 7.5% of all audiometric tests done within the food products manufacturing industry indicated early warning change (EWC) resulting in a total number of 329 EWC (70) cases-- a moderately high value among all the industries. Moreover, the previously completed pilot study was focused on this industry. As this study was initiated in response to the results reported by the pilot study, the same industry was selected for this study. The study sample was mainly comprised of companies with HCPs. These were identified from WorkSafeBC’s list of companies where workers went through audiometric tests. However, a few of the companies in the sample were not from that list--they were recruited from the online list of BC Manufacturers’ Directory (BCMD). Although our target was to get all the companies with HCPs, it did not materialize because of practical reasons. In order to recruit more companies, the BCMD list was used. Companies from this list were chosen using convenience sampling.  3.3 Study sample The target population of this study was those with decision-making and spending power and workers. The potential study sample was expected to include JHSC members and some people at workplaces who were not on JHSC. As JHSC comprises of people from both the 16  management and the non-management, we wanted to make sure that the non-JHSC group was also comprised of both groups of people i.e. the management and the non-management. Thus, the non-JHSC group was expected to be comprised of the following people: senior managers (production/maintenance), senior financial officers, and workers (production).  3.4 Recruitment and follow up The study population was recruited by the person responsible for health and safety (HS) at each company. This person served as a contact person for a company for this study. BC manufacturers’ directory and yellow pages were used to find out contact information of companies. The contact person was contacted first by an invitation letter, then by telephone. The invitation letter is attached in Appendix B. Upon his/her consent, this individual was asked to distribute questionnaires in the company according to the instructions provided in the questionnaire package. The instruction set is attached in Appendix C. The contact person was asked to distribute questionnaires to all the members of JHSC and the following people: a senior production manager who was not on that committee, a senior maintenance manager who was not on that committee, a senior financial officer who was not on that committee and two production workers who were not on that committee. The two workers in the non-JHSC group were asked to be chosen based on their birthdays to ensure the randomness of selection —those workers whose birthdays were closest to the day when the contact delivered the questionnaires. The researcher did not have access to the contact information of the actual study participants. The contact persons themselves were not asked to participate in this survey. Repeated phone calls were made to reach the contact person. One major difficulty faced by the researcher during recruitment was to get in touch with the contact persons in the companies. As the company contact persons were high ranking officials (in charge of HS), in most of the cases, the receptionists received calls and then transferred the researcher to the contact person’s line or voice mailboxes. A Message (about the study, researcher identity and contact information of the researcher) was left in the voice message box in each call with a request to return the call. The reasons provided by the contacts for non-participation were that they thought that people at their workplaces might not be interested in completing the survey or they did not have time to fill out the survey. In a few cases they provided no explanation. 17  Follow-up phone calls were made to the contact persons approximately three weeks after the mailing of questionnaires with a request to remind the participants to complete and return the questionnaires. At the last phase, a few companies, who did not send any questionnaires back, were sent another set of questionnaires with a request to distribute these to the same set of people who were first approached. The letter with the request to redistribute the questionnaires is attached in Appendix D.  3.5 Questionnaire 3.5.1 Development of the questionnaire A literature search was carried by using combinations of the following keywords in PubMed and Web of Science databases: knowledge/perception, noise, workplace/occupational, hearing loss, questionnaire survey; noise control, knowledge/perception, questionnaire survey. However, from the search, it appeared that research on knowledge and perception of occupational NIHL involving questionnaire survey was limited. A number of questionnaire surveys were focused on hearing protection use (71)(72)(73)(74)(75). Some of these studies utilized the questionnaire developed by Lusk (72), which measured perceived control of health, perceived self-efficacy of use of HPD, perceived health status, perceived benefits and barriers to HPD use, situational factors (availability and accessibility of HPD) and use of HPD. One study investigated the effect of audiometric data on the perception of workplace noise and noise exposure avoidance by rural Australians (76). This study used a questionnaire to measure subjects’ perceived benefit of reducing noise exposure through HPD, barriers to reducing noise exposure though HPD, self efficacy, attitude towards workplace noise and perceived susceptibility to hearing loss. Another study was focused on management and motivational factors in the control of NIHL (33). In addition to using noise audits of companies and interviews, it used a questionnaire survey to investigate workers’ attitude towards noise. However, it only investigated workers’ susceptibility to NIHL, perceived self-efficacy to protect themselves from noise (e.g. ability to do something to protect themselves from noise) and perceived consequences of noise exposure (hearing loss, annoyance, stress). Some other studies (77)(66)(67)(78)(79) involving questionnaire survey reported some findings about knowledge 18  and/or perception regarding occupational noise exposure and/or NIHL; however, from the description of the results, it appeared that these studies did not investigate knowledge and perception about NIHL and occupational noise in great detail. Moreover, all these studies involved participants of foreign languages (77)(66)(67)(78)(79). No questionnaire survey studies on knowledge and perception of ENC were found in the literature search. One study reported management’s perception and views regarding ENC, but, it employed an interview process rather than a questionnaire survey to gather that information (33). Because of the unavailability of relevant questionnaire studies, we contacted other researchers on noise and got a few samples of questionnaires on occupational noise3. However, these questionnaires (By Dr. William Bill Daniel and Sally L. Lusk) did not appear to be useful to the current study. So, the questions in this questionnaire for this study were largely developed by us using the validated questionnaires as models. Only a few questions from those validated questionnaires were directly used with minor modifications.  3.5.2 Pre-testing the questionnaire We took measures to evaluate the questionnaire to ensure its effectiveness. A common approach to questionnaire pretesting is to employ a convenience sample: co-workers and people who are similar to the study subjects (80). Upon a review of the draft questionnaire by the research team members, the questionnaire was circulated to some colleagues (n=2) who had experience in hygiene-related research. These participants were asked to write down how they would interpret each question or note any ambiguity in the questions. The questionnaire was then modified and reviewed by the research team members. The modified questionnaire was then pilot tested. Pilot testing is one of several ways to ensure the validity of the questionnaire (80)(81). It employs exactly the same method and same questionnaire under simulated or actual research project conditions (80). It is the most important  3  Dr. Sally L. Lusk and Dr. William Bill Daniel’s questionnaires on occupational noise, namely Stephenson OMB  survey form, and Lusk-CPWR Employee survey, HLWS_HS Employer survey, HLWS_HS worker survey  19  step to find out what approaches (Likert scale, semantic differential scale, or multiple-choice questions) work well (81). Several individuals (n=10) of a carpentry workshop were recruited. After they had answered the questions in the questionnaire, a group discussion was arranged. The focus group session moved from general to specific topics. Participants were asked whether they had any difficulty in understanding the questions. In addition, they were also asked about their overall thoughts on the questionnaire: whether it was interesting or not; whether the layout drew their attention; how much time they needed to complete it; and any additional comments they wished to make. Respondents were asked about clarity/ambiguity about some specific questions which were identified by colleagues (who participated in the pre-test before the pilot test) as unclear. The pilot test respondents were also asked how they had interpreted those questions. A final version was then obtained after discussions and revisions by the research team and their colleagues.  3.5.3 Questionnaire content Items in the questionnaire were grouped in the following main categories: Demographics; Knowledge of risk; Perception of risk; Knowledge of ENC; Perception of ENC Other knowledge and perception and “Audit”. Audit questions in the questionnaire were used to gain some background information about the companies, e.g. noise problem, efforts to prevent NIHL, the overall health and safety situation, etc. The majority of the questions were close-ended. Likert scale was applied where appropriate. This scale is suitable for perceptions or attitude measurement (81). A self-developed rating scale was used for 3 sets of questions on ENC and NIHL. Multiple choice questions and checklist were also used. Use of open-ended questions was minimized.  20  The questionnaire for this study is attached in Appendix E. Table 2 provides a classification of questions based on their contents. Moreover, detailed information about each question and the classification group it belongs to is provided in another table in Appendix F.  21  Table 2: Classification of questions based on contents Category Knowledge of risk  Sub-categories  Perception of risk  Knowledge of ENC  Perception of efficacy of ENC Other perceptions about ENC  Other  Perception of feasibility Perception of cost as a barrier Perception of other benefits  Description To test whether subjects are aware 1. that exposure to loud noise can damage hearing, 2. of harmful level of noise that can cause hearing loss (as specified in OHS noise regulations of BC), 3. that temporary loss of hearing and tinnitus (ringing in the ear) can occur with exposure to noise for some time, 4. that NIHL develops slowly, 5. that its progression is difficult to notice, 6. of an early sign of hearing loss, 7. of a few limitations of HPD: tightness of fit, protection lost due to not wearing HPD for the entire shift, 8. of some other effects of noise exposure apart from NIHL, and 9. of other causes of hearing loss ( ototoxic chemicals) *To find out whether subjects perceive that 1. NIHL may be responsible for loss of quality of life 2. they will be bothered by NIHL had they developed it, 3. carrying out conversation may become difficult due to NIHL, and 4. Signs of NIHL may be viewed negatively (e.g. jokes or laughter) by colleagues *To find out how they would rate NIHL among other diseases or health effects in terms of seriousness or level of concern *To find out the respondents’ perception of a worker’s chance of incurring NIHL at their workplaces; to find out whether they felt that their own hearing was protected To find out 1. whether subjects can provide some examples of ENC 2. whether subjects are familiar with noise regulations (where requirements for ENC is set out) 3. subjects’ preferred sources of information for ENC To find out how subjects’ would rate ENC compared to other prevention measures in terms of its efficacy to prevent NIHL To gain some idea about subjects’ perception of complexity associated with the implementation of ENC To have some idea whether cost is perceived as an important factor regarding the implementation of ENC To find out whether subjects think that reduction of noise could improve their productivity and efficiency 1.To have some idea about how much trust is put on audiometric tests (AT) 2.To test subjects’ perception of the effectiveness of hearing aids in treating NIHL 3.To know whether they liked a quieter workplace 4.To find out whether the respondents perceived that NIHL was preventable through HPD  22  Table 2: Classification of questions based on contents (contd.) Category e) Audit  f) Demographics  Sub-categories 1.Company effort to reduce noise 2.Corporate culture  Description To find out whether any noise measurement and special training about noise is done in the company and whether there is any ENC in place. To find out whether the company itself takes any initiative to prevent health hazards or, they don’t do anything unless workers complain. To gather background information about participants: duties in the current job, involvement in health and safety activities, education, gender, age and ethnicity.  3.5.4 Reliability of the questionnaire To check for the reliability or internal consistency of the questionnaire, three pairs of questions-with each pair bearing a different concept- were posed in the questionnaire. In other words, both questions in a particular pair bore the same notion. The fact that respondents’ opinions are consistent across questions in a pair would indicate reliability. This approach of reliability check was carried out by another study; it suggested that at least 3 pairs of questions should be checked for consistency (82). The questions are as follows: Pair 1: 1. a) It is a big handicap to lose part of one’s hearing 1. b) If I developed hearing loss, I wouldn’t be bothered by it Pair 2: 2. a) If a person is exposed to high level of noise for some time, his/her hearing could be temporarily reduced. 2. b) Check all that apply: Some effects of exposure to high level of noise for some time are: * Slow reflexes * Temporary reduction of hearing * Pain inside head * Permanent loss of hearing * Tinnitus (ringing in the ear) * Don’t know Pair 3: 3. a) Hearing loss is preventable by wearing hearing protectors 23  3. b) Please indicate how effective it (each of the prevention measures: HPD, ENC, job rotation, annual hearing test and education of employees) is in preventing hearing loss: Not at all effective, somewhat effective, moderately effective and highly effective. Both questions in pair 1 are Likert scale questions; however, both pair 2 and pair 3 contain questions of different designs—in each of those pairs, “a)” is a Likert scale question whereas “b)” is either a multiple choice question or a rating question. Cronbach’s alpha was also calculated for Pair 1. Cronbach's alpha is a useful statistic for investigating the internal consistency of questionnaire answers (83)(84)(85). It is often used when items in an instrument are not scored right versus wrong, for example, an instrument using Likert scale (86) and items under the same construct. Cronbach's alpha will generally increase when the correlations between the items increase.  3.5.5 Delivery of the questionnaire A paper-based mail-out survey was chosen for this study. The questionnaire was accompanied by a one-page cover letter explaining the purpose and the importance of the study and assuring the participants of confidentiality and anonymity. The cover letter also included details of the amount of time needed to fill out the questionnaire and contact information of the researchers. A return envelope with paid postage was sent along with each questionnaire. In addition to the instruction set for distributing the questionnaire, an information letter (Appendix G) was sent to the contact person. The information letter was sent to thank the contact persons for their help and also to refresh their memories about what the study was about. A package was made up all these materials (information letter, questionnaires, return envelopes, instruction set) and this package was mailed to the contact person. As an incentive, study subjects were invited to participate in a raffle draw for an iPod (CAD $200). The participants were asked to include their names and contact information on a separate page. This page was severed from the questionnaire to ensure anonymity and was used just for the purpose of the raffle draw. The University of British Columbia considers any raffle draw a lottery if the draw does not include those who decline to participate. So, it was decided that all the participants, including those who had not completed the questionnaire, would be considered for the raffle draw. Only the winner was contacted 24  3.6 Data coding, error checking and management Codes were assigned to individual companies. The questionnaire sent to a particular company bore the corresponding code number. Within each company, each person was assigned a code number to maintain confidentiality. A questionnaire ID was formulated combining both the company code and the person codes. Each question in the questionnaire was given a distinct code. Answer options in a particular question were assigned distinct numbers as codes. First, data were entered in MS Excel by the researcher. Then a subset of questionnaires (n=11) was checked for errors. Approximately 0.5 % of the data had errors. As the proportion of error was very low, the accuracy of the original dataset seemed reliable. The dataset was imported to STATA for analysis. In STATA, the data set was checked for out of range or erroneous values. A few errors were found and corrected by the researcher. Each demographical question in the questionnaire had a number of categories. Those categories were combined into fewer subgroups. Table 3 provides a list of these subgroups. The focus of the comparison, however, was subgroups based on job responsibility and involvement in health and safety activities.  Table 3: List of subgroups Characteristic Job responsibility  Name of the subgroups Management Non-management  Involvement in health and safety activities  Yes No  Education  Age  Ethnicity Gender  Secondary or less Post-secondary (non-degree) Post-secondary (degree) <=39 years >=40 but<50 years >=50 years Caucasian from Canada Other Male Female  25  The groups are described below: 1. Responsibility in the current job: Management: This group was comprised of mostly managers; other type of jobs that were included in this group were directors of finance, chief financial officer, and chief engineer. Non-management: The remaining respondents were categorized as the “Nonmanagement”. This category included supervisors, foremen, technician, customer service/sales, office administrative/accounting assistants, lead hands, drivers, machine operators, warehouse, and others. 2. Involvement in health and safety activities: Two groups were created based on “involvement in health and safety activities”: Yes and No. No: If a respondent chose “none” as an answer to the question “Have you been involved in any of the following occupational health and safety activities over the last year ?”, he/she was categorized as “No” Yes: The rest of the respondents were categorized as “Yes”. 3. Education: The 3 levels of education were created based on the researcher’s judgment. Statistic Canada’s opinion about the variable containing information (which was gathered through census) on a person's most advanced certificate, diploma or degree is as follows (87): “There is an implied hierarchy in this variable (secondary school graduation, registered apprenticeship and trades, college, university), … … …it is a general rather than an absolute gradient measure of academic achievement.” Based on this, the following hierarchy in education levels was assumed: Secondary education or less: some high school or high school graduate, Trade certificate, midway through apprenticeship, Steam certificate and trade techno[logist]. Post secondary education (non-degree): some college credit but no degree, college graduate, CGA, BCIT technical HR management certificate. Post secondary education (degree): bachelor’s degree, mechanical engineer, M.Sc., Ph.D. or professional certificates that requires a university degree e.g. CMA, CA. The majority of the respondents provided clear indication of their education level. However, a few participants chose several options. In those cases, the highest level was recorded. 26  4. Age: Age groups less than 30 years and 30-39 years old were combined to create the new group <=39 years. These 2 groups were combined as the sample sizes in those groups were very small. 5. Ethnicity: Although the respondents were of a wide variety of ethnicity, namely, Caucasian from Canada, European, African, Chinese, South Asian, native, Middle Eastern, Australian, Japanese; very few respondents belonged to those ethnicity apart from “Caucasian from Canada”. Thus, all the other respondents apart from Caucasian from Canada were combined to create the new group “Other” to provide meaningful results.  3.7 Data analysis 3.7.1 Aggregate response For each question/variable, proportions (%) were calculated as suggested by other researchers (81)(82)(88)(89). The missing values were excluded (90)(89). Because of rounding to the nearest whole percent, the sum of percentages over all the answer options may not be equal to exactly 100%; however, this error due to rounding is rarely considered a concern (90). Median values were calculated for rating questions or questions which asked respondents to assign ranks (81)(91). Modes were also calculated for such questions to show popular choices (91).  3.7.2 Response among subgroups For comparison across subgroups, proportions (%) were calculated in each subgroup. Missing values were omitted. As most of the data was categorical, a non-parametric method was suitable. Chi-Squared test is recommended to find out whether two or more subgroups are different when the data are categorical (91)(81). Several studies (92)(82) on perception, knowledge and attitude used Chi-squared test for subgroups; so, this test was used in this study. Chi-square test is appropriate when the expected frequency in each cell of the contingency table is equal to at least 5; when the expected frequency is smaller than 5, Fisher’s Exact test is appropriate. In such situations, Fisher’s Exact test was used. For knowledge of risk questions, answers were dichotomized: correct vs. incorrect. For these questions, “don’t know” and wrong 27  answers were combined into one group (“incorrect”) since wrong answers and “don’t know” imply almost the same notion—no knowledge. For risk perception questions involving Likert scale, answers were dichotomized: answers showing high risk perception vs. answers not showing such level of risk perception. In questions, where a response of “agree” or “strongly agree” implied high risk perception, these two answer options were marked as “high risk perception” group; the rest of the answer options (“disagree/strongly disagree”, “neutral” and “don’t know”) belonged to the other group. For comparison involving ranked or ordered data (such as questions involving ranks and rating scales), Mann-Whitney test was used for comparison between 2 groups and Kruskal-Wallis test was used for 3 or more groups. Not all questions/variables were considered for subgroup analysis. Level of significance (alpha) was chosen to be 0.05.  3.7.3 Multivariable analyses After preliminary analyses, the research team thought that the data contained interesting information and that multivariable analyses should be carried out to answer the following questions: 1. What is the association between knowledge of risk and (1) job responsibility and (2) involvement in health and safety activities after adjusting for gender, age, ethnicity, education? 2. What is the association between risk perception (RP) and (1) job responsibility and (2) involvement in health and safety activities after adjusting for gender, age, ethnicity, education? 3. What is the association between perception of efficacy of ENC and (1) job responsibility and (2) involvement in health and safety activities after adjusting for gender, age, ethnicity, education? Investigation of association between knowledge of ENC and those aforementioned factors did not seem reasonable since the variable, knowledge of ENC, had a lot of missing values; moreover, only 3 respondents could answer this question correctly.  3.7.3.1 Overview Each of the above research questions was analyzed using multiple logistic regressions (MLR) with backward elimination procedure. First, association between explanatory variables 28  was investigated using Chi-squared test. If any association was significant at p<0.01, one of the two variables was excluded. Second, the relationship between each dependent variable and each independent variable was explored using simple logistic regression (SLR). Usually only those independent variables, that turn out to be significant in univariate analyses (SLR) are put in MLR initially; in our case, only one independent variable turned out to be significant in the majority of univariate analyses. So, it was decided that all the independent variables would be initially included in each of the MLR analyses; then independent variables would be dropped one at a time based on the exclusion criteria (p<0.05). Only ethnicity and education each had one missing value; these were replaced by the mode of that variable.  3.7.3.2 Knowledge of risk A dichotomous dependent variable, “KR” was created; “KR”=1 indicates “good knowledge” and “KR”=0 indicates “poor knowledge”. A respondent was assigned a “KR”=1 if he/she answered greater than or equal to 80% of the knowledge of risk questions (at least 5 out of 6 questions) correctly. Missing values of individual knowledge of risk questions were replaced by the mode. The content of knowledge of risk questions used to create the dependent variable“KR”-are knowledge of noise level, temporary reduction of hearing, tinnitus, an early sign of hearing loss; awareness that loud noise can hurt one’s hearing and that exposure to loud noise builds resistance to NIHL.  3.7.3.3 Perception of risk The dependent variable, “RP” was a dichotomous variable. “RP”=1 indicates “high risk perception” and “RP”=0 indicates “low risk perception”. A respondent was assigned an “RP”=1 if he/she showed high perception of risk in greater than or equal to 80% of the perception of risk questions (at least 4 out of 5 questions). Missing values (for any individual risk perception question) were replaced with the mean score on that question. The individual perception of risk questions (Likert scale questions) that were chosen to create the dependent variable -”RP”, are shown in Table 4.  29  Table 4: Risk perception statements used for creating the dependent variable for MLR analysis of perception of risk Risk perception statement Noise is a major contributor to loss of quality of life Losing part of my hearing would make it harder for people to talk to me. It is a big handicap to lose part of one’s hearing. Signs of hearing loss are often met with jokes by coworkers/colleagues If I developed hearing loss, I wouldn’t be bothered by it.  Indicator of high perception of risk in each individual risk perception statement Strongly agree or agree Strongly agree or agree Strongly agree or agree Strongly agree or agree Strongly disagree or disagree  3.3.4 Perception of efficacy of engineered noise control The dependent variable for perception of efficacy of ENC-“ENC-P”-was dichotomized. If a respondent considered ENC to be “extremely effective” in preventing NIHL- he/she was assigned a “ENC-P=1”; if he/she considered ENC to be “moderately effective” or “somewhat effective” or “not at all effective” in preventing NIHL- he/she was assigned a “ENC-P=0”.  30  4. Results 4.1 Overview This section describes the results on questionnaire reliability, recruitment summary, response rate, background information on participant companies (i.e. noise-prevention effort, noise exposure situation, or corporate culture regarding safety), aggregate and subgroups’ responses regarding research questions and multivariable analyses. The results on background information on companies were based on individuals (i.e. % of respondents) rather than the companies; no precise picture could be drawn about any particular company as there were conflicting answers from different respondents within the same company.  4.2 Questionnaire reliability A total of 90 respondents answered both 1.a) and 1.b) and 82% of them provided consistent answers. The value of Chronbach’s alpha for these two questions was around 0.80. Moreover, 89 respondents answered both questions in Pair 2 and 64% of them provided consistent answers. For Pair 3, 56 respondents answered both questions in Pair 3 and 48% of them provided consistent answers. The respondents showed consistent responses among most of the pairs. The questionnaire seems to have fair internal reliability.  4.3 Recruitment summary and response rate There were 140 unique companies in the WorkSafeBC list. Among those, 8 companies were found to be bankrupt or were numbered companies. After searching online, contact information of only 88 companies were found and among these, phone numbers of 12 companies were found to be not in service. So, the final list contained 76 companies. Repeated phone calls were made to all of these companies; however, the researcher was able to get hold of only 45 companies. Among those companies, 24 companies agreed to participate in the survey. From the list of non-WorkSafeBC list of 28 companies, the researcher could reach the contact persons of 15 companies of which 6 companies agreed to participate. Thus, in total, 30 companies were recruited. 31  A total of 283 questionnaires were sent and 92 questionnaires were received back with a response rate of 32.5%. However, this may not be the true response rate since the contact person, not the researcher, approached individuals and distributed the questionnaires, and as such, it was not known whether all the questionnaires were distributed. In total, 22 companies sent back questionnaires with a company response rate of 73%. Almost all the recruited companies (n=19) were from WorkSafeBC list, i.e., these companies had HCP and the majority of the respondents (85%) were also from these companies.  4.4 Information on the participant companies When asked about whether there was any noise measurement done at their workplaces, 33% of the respondents said that they did not know, and 40% said that it was not done. When asked about how often special training about noise was conducted in their companies, 46% said it was never done. When asked whether there was any ENC in their workplaces, most said “no” (44%); a similar proportion said that they did not know (42%), whereas the rest said “yes”. The majority of the respondents (63%) said that in their normal work they did not have to shout while talking to someone who was 1, 2 or 3 arms length away. The majority (68%) said that the persons in charge of health and safety in their workplaces identified hazards and brought these to the attention of their management, however, 16% implied that it was workers who took this initiative. The description of the products/processes of the participant companies is given below: Salad and vegetable preparations (cutting and packaging of raw vegetables), production of soy and other milk alternatives, jams, fruit spread and other fruit products, salsa, eggs, cream, cheese, whey-based drink, flour and cereal, bakery products, decaffeinated coffee, wine and related products; brewing of beers, poultry slaughtering and processing, catching/processing/marketing/distributing of seafood or fish (e.g. albacore tuna, salmon, halibut, black cod (sablefish), rockfish, ikura, spot prawns etc.) and oil blending (canola, soy and other vegetable oils). The participant companies come from different areas of British Columbia: lower mainland, interior and Vancouver islands. 32  4.5 Demographics The majority of the respondents belonged to the non-management group, were involved in health and safety activities, predominantly males and Caucasians from Canada. Most of the respondents had post secondary (non-degree) education and were aged between 40-49 years. The majority used HPDs (59%) and had their hearing tested (86%). Demographical information is provided in Table 5. Table 5: Demographical characteristics of the respondents Variable Job responsibility Management Non-management Involvement in health and safety activities Yes No Gender Male female Age <=39 years 40-49 years >=50 years Education <=Secondary Post-secondary (non-degree) Post-secondary (degree) Ethnicity Caucasian from Canada Other  n 30 62 63 29 68 24 32 37 23 27 41 23 58 33  The characteristics of respondents in the subgroups based on job responsibility and involvement in health and safety activities stratified by gender, age, education and ethnicity are shown in Table 6. Both the management and non-management subgroups had similar gender distribution: males making up the larger proportion in each subgroup. Half of the management group was between 40 to 49 years old; whereas, most of the non-management was 39 years old or younger. The majority of the management had post-secondary (non-degree education). However, proportion of respondents in the non-management subgroup having such level of education was lower than that of their management counterparts. The majority in each group 33  were Caucasians from Canada; however, this proportion was much lower in the nonmanagement category compared to the management. The majority in the group based on involvement in health and safety (HS) activities were males (Table 6). Most of the respondents who were involved in HS activities were 40 to 49 years old whereas most of the non-management were 39 years old or younger. Most of both the groups had post-secondary (non-degree) education; however, this proportion was much higher in the subgroup involved in health and safety activities. The majority in both the subgroups were Caucasians from Canada.  Table 6: Characteristics of respondents in the subgroups (based on job responsibility and involvement in health and safety activities) Variable  Job responsibility  Gender Male female Age <=39 years 40-49 years >=50 years Education <=Secondary Post-secondary(non-degree) Post-secondary (degree) Ethnicity Caucasian from Canada Other  Management n (%)  Non-management n (%)  Involvement in health and safety activities Yes No n (%) n (%)  23 (77) 7 (23)  45 (73) 17 (27)  48 (76) 15 (24)  20 (69) 9 (31)  7 (23) 15 (50) 8 (27)  25 (40) 22 (35) 15 (24)  19 (30) 27 (43) 17 (27)  13 (45) 10 (35) 6 (21)  3 (10) 17 (57) 10 (33)  24 (39) 24 (39) 13 (21)  17 (27) 30 (48) 15 (24)  10 (34) 11 (38) 8 (28)  23 (79) 6 (21)  35 (56) 27 (44)  41 (66) 21 (34)  17 (59) 12 (41)  The majority in the groups based on job responsibility and involvement in health safety activities were from companies with HCPs (87% of the management, 84% of the nonmanagement, 81% of the group involved in health and safety activities, and 93% of the group not involved in such activities).  34  4.6 Aggregate response 4.6.1 Knowledge of risk Results on knowledge of risk are shown in Table 7 and Table 8. The respondents’ knowledge of risk was evaluated using questions in the area of effects of noise exposure on hearing, a sign of hearing loss, development of hearing loss, the harmful level of noise exposure, and limitations of HPD. Moreover, questions regarding knowledge of risk also included knowledge of non-auditory effects of noise exposure and other causes of hearing loss apart from noise exposure. It appears that there was a high awareness among the respondents about the harmful effect of noise exposure: damage to hearing capability (Table 7). Moreover, most of them were aware about temporary effects of noise exposure on hearing (tinnitus i.e. ringing in the ear, temporary loss of hearing) (Table 8) and an early sign of hearing loss (Table 8). There was also a high awareness among the respondents about some facts about NIHL development: slow and insidious nature of NIHL development (Table 7). However, there seemed to be widespread ignorance among the respondents about the maximum noise level specified by the regulatory agency- WorkSafeBC (Table 8). Most of the respondents were aware of some non-auditory effects of noise exposure (hypertension (Table 8), stress (Table 8), and annoyance (Table 7)). However, the majority seemed to be unaware about other causes of hearing loss, for example, exposure to solvents (Table 8). The respondents were aware of the variability of the effectiveness of HPDs with tightness of fit (Table 7). Although they appeared to know the importance of wearing HPDs throughout the entire duration of noise exposure (Table 7), they did not have knowledge about the degree of protection lost due to not wearing HPDs for only a short period of time (Table 8).  35  Table 7: Knowledge of risk (Likert scale questions) Statement  SD or D % 0 7  NAD %  SA or A % 99 92  DK %  Exposure to loud noise at work can hurt my hearing. 1 0 If a person is exposed to high levels of noise for some time, his/her hearing 1 0 could be temporarily reduced. The progression of hearing impairment is difficult to notice. 17 6 73 6 Hearing loss develops slowly with continuous noise exposure. 4 7 86 3 High levels of noise can cause annoyance at work. 0 4 96 0 Exposure to loud noise at a young age builds resistance to hearing loss. 80 2 10 8 If one really wants to keep one’s hearing, it is important for one to wear 1 6 93 0 hearing protectors every time one is around loud noise. Hearing protectors’ effectiveness could greatly vary with tightness of fit. 0 4 91 4 + SA: Strongly agree, A: Agree, NAD: Neither agree nor disagree, D:Disagree, SD: Strongly disagree, DK: Don’t know, n: total number of respondents answering this particular question  n  91 89 91 91 90 91 91 91  Table 8: Knowledge of risk (multiple choice questions)  According to BC regulations, the maximum level of noise that a worker can be exposed to for 8 hours (full shift) is 85 dBA Some chemicals have shown to make ears more sensitive to noise. Tick all that you believe are related to hearing loss: Solvents (toluene, isocyanite) Some effects of exposure to high level of noise for some time are: Temporary reduction of hearing, Tinnitus (ringing in the ear)  An early sign of hearing loss is: Inability to hear high-pitched sound Occupational noise can cause: Hypertension, Stress If you normally wear hearing protectors for a full 8-hour shift, how much protection do you think you will lose if you forgot to wear it 10% of the shift (30 minutes)? Answer: 45-55%  Correct Knowledge % 28  No Knowledge % 49  Wrong answer  n  23  90  15  75  10  92  Tinnitus  76  7  18  92  Temporary loss of hearing  67  8  25  68  19  13  91  48 80 6.5  11 11 40  41 9 53.5  92  Hypertension Stress  36  4.6.2 Perception of risk The respondents’ perception of risk was evaluated in different ways: level of concern for hearing loss compared to other occupational health problems and chronic diseases and perception of negative consequences of hearing loss on their lives. The results on risk perception are shown in tables 9-11 and figures 1-2. Moreover, the respondents’ perception about the likelihood of a worker’s chance of developing NIHL and perception about the safety of their own hearing were also evaluated. The respondents were asked to rank some occupational health problems to indicate how serious or concerning these were to them. The health problems were as follows: hearing loss, stress, chemical burns, repetitive strain injury (RSI), and accidents; the diseases were chosen on the basis of number of claims accepted by WorkSafeBC for short term disability (STD), long term disability (LTD) or survivor benefits for the year 2005 (93). Accidents were included as an option because they resulted in several thousand claims in 2005 (94). A rank of 1 indicated highest degree of concern and a rank of 5 indicated lowest degree of concern. Figure 1 shows how the respondents assigned different ranks to these occupational health problems. While comparing how the respondents assigned a rank of 1, it becomes clear that the proportion of respondents who chose hearing loss as the most concerning health problem was lower than those who selected accidents as the most concerning health problems. Moreover, while comparing the median and mode ranks (Table 9), it appears that hearing loss received higher ranks compared to both accidents and chemical burns; however, it received lower ranks compared to RSI and stress (Table 9). These findings indicate that hearing loss was a matter of lower concern compared to accidents and chemical burns but was of higher concern compared to stress and RSI among the respondents.  37  Figure 1: Ranks assigned by respondents (%) to some occupational health problems indicating how serious/concerning those were to them (with “1” being the most serious/concerning one and “5” being the least serious/concerning one) Table 9: Median and mode values of ranks for some occupational health problems Health effects  Median rank  Mode rank  Chemical burns 2 2 Stress 4 5 Repetitive strain injury 4 4 Hearing loss 3 3 Accidents (e.g. struck by/against) 2 1 N.B. “1” being the most serious/concerning one and “5” being the least serious/concerning one  n  89 90 89 89 90  38  The respondents were asked to indicate how worried they would feel if they were diagnosed with the following chronic diseases: skin cancer, lung cancer, memory loss, hearing loss, arthrhitis, and chronic depression. Figure 2 shows how the respondents assigned different ratings (extremely, moderately, somewhat, or not at all worried) to different diseases. It is clear that the proportion of respondents who assigned an “extremely worried” rating to hearing loss is much lower than the proportions of respondents who assigned such a rating to lung cancer, memory loss and skin cancer. The median and the mode values of ranks for hearing loss were also lower than those of lung cancer, memory loss, and skin cancer (Table 10) (a larger rating value indicates a higher level of concern). These findings indicate that hearing loss was considered to be of lower level of concern by the respondents compared to those diseases. However, hearing loss seemed to be of similar level of concern compared to chronic depression and stress (medians and modes were the same for all these three conditions; in addition, the proportions who assigned an “extremely worried” rating to these conditions were almost the same except for stress).  39  Figure 2: Level of concern expressed by respondents if they were diagnosed with certain chronic diseases  Table 10: Median and mode values of ranks for some chronic diseases Diseases Median rank Mode rank n Skin cancer 4 4 89 Lung cancer 4 4 89 Hearing loss 3 3 88 Memory loss 4 4 88 Arthritis 3 3 88 Chronic depression 3 3 88 N.B. Not at all Worried = rank1, Somewhat Worried = rank2, Moderately Worried = rank3, Extremely Worried = rank4  40  The respondents were asked to provide their opinion on the following risk perception statements (Table 11). A response of strongly agree or agree indicates a high risk perception in all the statements except statement 2 where a response of strongly disagree or disagree indicates a high risk perception. Overall, the majority of the respondents showed high risk perception about the impact of NIHL on quality of life. The majority perceived that hearing loss would be an impediment to carrying out conversation with people and considered it to be a major disadvantage. These findings are consistent with the fact that the majority opposed the idea that they would not be bothered by hearing loss had they developed it. There seemed to be a mixed opinion among the respondents about how a hearing loss victim would be treated by his/her colleagues: a modest proportion of the respondents thought that signs of hearing loss may be viewed with contempt by co-workers; a small fraction disagreed/strongly disagreed with this idea and the rest remained neutral to this idea. The majority, in general, perceived noise to be a significant cause of loss of quality of life.  Table 11: Perception of risk among the respondents Risk perception statement  SD or D % 2  NAD %  SA or A % 97  DK %  1. Losing part of my hearing would make it harder for people to talk to 1 0 me. 2. If I developed hearing loss, I wouldn’t be bothered by it. 89 0 11 0 3. It is a big handicap to lose part of one’s hearing. 1 7 92 0 4. Signs of hearing loss are often met with jokes by co20 33 43 4 workers/colleagues 5. Noise is a major contributor to loss of quality of life 2 7 90 1 + SA: Strongly agree, A: Agree, NAD: Neither agree nor disagree, D: Disagree, SD: Strongly disagree, DK: Don’t know, n: total number of respondents answering this particular question  n  91 91 90 91 90  Greater than half (59%) of the respondents disagreed/strongly disagreed that a worker’s chance of developing NIHL was low at their respective workplaces. The majority (81.5%), in general, felt that their own hearing was protected.  41  4.6.3 Knowledge of engineered noise control The respondents’ knowledge of ENCs was evaluated using an open-ended question which asked them to provide examples of ENCs. In addition, the respondents’ awareness about OHS regulations on noise was also evaluated. It was assumed that familiarity with noise regulation might indicate the respondents’ awareness about ENCs and when to implement them. Moreover, respondents’ knowledge about sources of information on ENCs was also investigated. Only three respondents could provide “good” examples of ENCs (enclosure of workers, equipment or foam insulation); very few respondents (n=3) had “some” knowledge of ENCs (use of less reflective material on the wall, closing of noisy areas, insulation, loud printers and machines in separate room from desk areas). Here, “good knowledge” implies respondents’ ability to provide concrete examples of ENCs (e.g., enclosure) and “some knowledge” implies their ability to provide ideas (i.e. closing of noisy areas) which somewhat matches with the principle of ENCs rather than exact examples of ENCs. However, many of the respondents provided examples that can be categorized as administrative controls (purchasing of new equipment, replacing the noisy one with a quieter one, good maintenance of equipment, job rotation, moving the noisy machine where there are less workers, education of employees and even changing jobs). Many of the respondents provided the same examples as provided by the researchers at the beginning of “ENC” section in the questionnaire. A point to note here is that out of 92 respondents, only 28 attempted to answer this question. The majority of the respondents (65%) never read or saw OHS regulations of BC on noise. The popular sources of information for ENC seemed to be Internet followed by workers’ compensation board, health and safety professionals, and JHSC respectively (Table 12).  Table 12: Knowledge of information sources of ENC  Internet Workers Compensation Board Health and safety professional Joint health and safety committee Acoustical consultants Workers’ union Other  % of respondents 64 59 50 42 27 9 3  42  4.6.4 Perception of efficacy of engineered noise control The respondents’ perception of efficacy of ENC was evaluated using a question which asked the respondents to assign ratings (highly, moderately, somewhat or not at all) to commonly used prevention measures in terms of their effectiveness in preventing NIHL. The following options were included in that question: HPD, ENC, education of employees, so that they can protect themselves from noise exposure, annual hearing tests of employees, and job rotation. Figure 3 shows how the respondents assigned different ratings to those measures. Going through the “highly effective” ratings, it appears that the proportion of respondents assigning a “highly effective” rating to ENC is lower than that of HPD, education, and hearing tests. Moreover, the median and mode values for ENC were lower than those measures (except for hearing tests for which the median value was the same as ENC) (Table 13). A larger rating value indicates a higher level of perception. From these findings, it appears that the respondents had lower perception of efficacy of ENC compared to HPD, education, and hearing tests. However, ENC was thought to be more effective than job rotation by the respondents.  43  Figure 3: Ratings assigned by respondents to different prevention measures in terms of their effectiveness in preventing NIHL  Table 13: Median and mode values of ratings assigned by the respondents to different prevention measures used to prevent NIHL Median Rank Mode Rank Hearing Protective Devices 4 4 Job rotation 2 2 Educating employees so that they 4 4 can protect themselves from noise exposure Engineered noise control 3 3 Annual hearing tests of employees 3 4 N.B. (1 = not at all effective, 2 = somewhat effective, 3 = moderately effective, 4 = highly effective)  n 89 89 90  91 89  44  4.6.5 Other perceptions about engineered noise control Table 14 shows results on other perceptions about ENCs. ENCs were thought to be beneficial to the improvement of workers’ productivity and efficiency by the majority of the respondents. However, it appeared that there were mixed opinions among the respondents about the complexity associated with ENC installation: a small fraction of the respondents thought that installation of ENCs was difficult and complex; however, a similar proportion of the respondents remained neutral to this idea and a similar proportion opposed this idea. Approximately half of the respondents did not seem to have any opinion or know whether cost could be a major factor in their decision to implement ENCs. However, a similar proportion was opposed to the idea that they would not install ENCs because of its cost.  Table 14: Perception of feasibility and other benefits of ENC Statement  SD or D % 33 46  NAD %  SA or A % 34 15  DK %  n  Installing engineered noise control is complex and difficult. 15 18 91 I wouldn’t consider adoption of engineered noise control because it is 24 12 91 expensive. Reduction of noise to a comfortable level may improve workers’ 0 11 87 2 91 productivity and efficiency. + SA: Strongly agree, A: Agree, NAD: Neither agree nor disagree, D:Disagree, SD: Strongly disagree, DK: Don’t know, n: total number of respondents answering this particular question  4.6.6 Other findings The majority of the respondents would like to have a quieter workplace (77%). The majority (92%) thought that NIHL is preventable by wearing HPDs. Approximately half of the respondents (49%) strongly disagreed/disagreed that hearing aids could effectively cure hearing loss; however, 29% did not know or remained neutral to this idea and the rest (20%) agreed/ strongly agreed with this idea. Approximately 96% of the respondents agreed/strongly agreed that annual audiometric tests would give advance warning of hearing loss.  45  4.7 Response among subgroups 4.7.1 Knowledge of risk Table 15 summarizes the results on knowledge of risk among subgroups. There was a statistically significant difference among subgroups based on job responsibility in terms of knowledge of an early sign of hearing loss: the non-management group was more aware of this fact than the management group. Although not statistically significant, the non-management group generally appeared to be more aware than the management group about other facts. There was a statistically significant difference among subgroups based on involvement in health and safety (HS) activities in terms of knowledge of maximum level of noise exposure specified by WorkSafeBC. These subgroups also differed significantly in terms of knowledge on non-auditory effects of noise exposure (stress). In both cases, the respondents involved in HS activities were more aware of these facts than those who were not involved in such activities. Although not statistically significant, the respondents involved in HS activities appeared to be more aware than those who were not involved in such activities about other facts. Among other subgroups, only the subgroups based on ethnicity differed significantly in terms of knowledge on temporary effects of noise exposure (tinnitus): Caucasians from Canada were more aware of this fact than the other ethnic group.  46  Table 15: Percentage of respondents in the subgroups aware about the following facts about noise exposure and hearing loss  59  70  74  66  71  74  55  74  68  57  70  79  78  72  81  73  74  74  83  83*  63*  70  85  65  50* 77*  69  66  69  64  74  69  67  68  70  78  58  74  hypertension  43  50  48  48  41  48  57  47  50  48  45  56  41  52  stress  80  81  87* 66*  78  78  87  84  71  83  76  78  78  87  23  30  36* 10*  29  22  34  32  17  26  31  22 15  39  1  8  7  3  5  11  5  7  13  6  8  9  Canada 3  5  PS(degree)  59  S  Caucasian from  71  Others  female  70  >=50  63  Temporary reduction of hearing Tinnitus  >=40 but<50  male  PS (non-degree)  Education level  <=39  Ethnicity  No  According to BC regulations, the maximum level of noise that a worker can be exposed to for 8 hours (full shift) is 85 dBA Knowledge about protection lost due to not wearing HPD just for 10% (30 minutes) of an 8-hour workshift *p<0.05  Gender  Yes  An early sign of hearing loss is Inability to hear high-pitched sound Occupational noise can cause: Hypertension, Stress  Age (years)  Non-managerial  Some effects of exposure to high level of noise for some time are: Temporary reduction of hearing, Tinnitus (ringing in the ear)  Involvement in health and safety activities  Managerial  Responsibilit ies in the current job  47  4.7.2 Perception of risk Table 16, 17 and 18 summarize results on perception of risk among subgroups. There was no statistically significant difference among subgroups based on job responsibility and involvement in health and safety activities in terms of level of concern for hearing loss (Table 16) and perception of negative consequences of hearing loss on their lives (Table 17). However, more respondents in the non-management group showed high concern for NIHL than the nonmanagement. The majority in all those subgroups seem to perceive the negative consequences of NIHL on life, however, the non-management and the group involved in HS activities seemed to perceive the negative consequences more than their counterparts. There was, again, no significant differences among these subgroups in terms of their perception of a worker’s chance of developing hearing loss in their workplaces and their perception regarding the safety of their own hearing (Table 18) except that the subgroups based on involvement in health and safety activities differed significantly on their perception about the safety of their own hearing. The proportion of those involved in such HS activities, who felt their hearing was protected, was larger than their counterparts. Other subgroups did not differ significantly on any perception question.  48  Table 16: Percentage of respondents in the subgroups assigning “rank 1 (most concerning)” to hearing loss Responsibilities  Involvement in  in the current job  health and  Age (years)  Gender  Ethnicity  Education level  16  34  PS(degree)  21  PS (non-degree)  23  Others  4  S  25  Canada  31  Caucasian from  <=39  21  female  No  23  male  Yes  27  >=50  Non-managerial  13  >=40 but<50  Managerial  safety activities  15  25  27  N.B. Mann-Whitney (for 2 group comparisons) and Kruskal-Wallis (for 3 group comparisons) tests were used to find out difference among subgroups in terms of ratings assigned to NIHL. These tests include all the different ratings (1-5) assigned to NIHL; however, in this table, proportions across subgroups are shown for “Rank 1=Most concerning” rating only just for simplicity  49  Table 17: Percentage of respondents in the subgroups showing high risk perception regarding consequences of NIHL on life  PS (non-degree)  93 92 91  91 96  91  82  92  93 87  100 95  98  90  100 97 91  97 96  93  100  92  98 100  90  93  94  89  97  89 91  91 96  89  97  90  95 91  83  92  92  82  81  78 83  78 88  81  79  78  83  33  48  44  45  38 48  42 46  46  39  42  49 35  39  PS(degree)  S  79  Others  94  male  93  >=50  93  >=40 but<50  Caucasian from Canada  Education level  female  Ethnicity  <=39  Gender  No  Age (years)  Yes  Noise is a major contributor to loss of quality of life Losing part of my hearing would make it harder for people to talk to me. It is a big handicap to lose part of one’s hearing. If I developed hearing loss, I wouldn’t be bothered by it Signs of hearing loss are often met with jokes by coworkers/colleagues “*” p<0.05  Involvem ent in health and safety activities  Non-managerial  Responsi bilities in the current job  Managerial  Risk perception statement  83  50  Table 18: Perception among subgroups (%) about a worker’s chance of developing NIHL and their own hearing  72  56 55  PS(degree)  83 79  PS (non-degree)  74 83  91  S  Canada  83  92* 58*  Education level  Others  Caucasian from  72  90  female  55  male  62  >=50  62 46  >=40 but<50  61 61  Yes  <=39  Ethnicity  No  Gender  55  53  77  Age (years)  71  47 65  Managerial A worker’s chance of getting hearing loss is very low at this workplace (Strongly disagree or, disagree) Do you feel that your hearing is protected? (yes) *p<0.05  Involvem ent in health and safety activities  Non-managerial  Responsi bilities in the current job  78 85 82  4.7.3 Knowledge of engineered noise control The analysis on the major knowledge of ENC question (open-ended question asking for examples of ENCs) did not seem reasonable as only very few respondents provided correct answers. Table 19 and Table 20 show results on other knowledge of ENCs. There was no statistically significant difference among subgroups in their knowledge of BC’s OHS regulations on noise; however, the management and the respondents involved in HS activities were more aware about these regulations than their respective counterparts (Table 19). There was no statistically significant difference among groups in terms of their knowledge of information sources of ENCs except the group based on ethnicity (Table 20).  51  Table 19: Percentage of respondents in the subgroups aware of BC’s OHS regulations Responsibilities  Involvement  in the current  in  job  health and  Age (years)  Gender  Ethnicity  Education level  safety  36  PS(degree)  35  PS (non-degree)  21  Others  40  S  35 44  Canada  29  Caucasian from  24  female  <=39  40  male  No  30  >=50  Yes  38  >=40 but<50  Non-managerial  Have you ever seen or read Occupational Health & Safety regulations of BC on noise? (yes)  Managerial  activities  35  36  35  Table 20: Knowledge of information sources of ENC among respondents (%) in different subgroups Responsibil  Involvement  ities  in  in the  health and  current job  safety  Age (years)  Gender  Ethnicity  Education level  >=50  male  Caucasian from  Canada  S  PS (non-degree)  PS(degree)  32  14  19  27  35  29  17  33  15  11  37  26  77  58  65  62  78  51  65  63  67  72* 49*  56  73  61  40  55  52  45  59  35  61  46  63  53  41  59  43  45  Others  <=39  23  female  No  33  >=40 but<50  Yes  Health and safety professional * p<0.05  Non-managerial  What sources would you use to access information about suitable ENC for your workplace? Acoustical consultants Internet  Managerial  activities  52  4.7.4 Perception of efficacy of engineered noise control Table 21 shows results on perception of efficacy of ENC. There was no statistically significant difference among any subgroups in their perception of efficacy of ENC in preventing NIHL. However, going through the “highly effective ” ratings, it can be seen that more respondents in the non-management group and in the group involved in HS activities considered ENC to be highly effective than their respective counterparts.  Table 21: Percentage of respondents in the subgroups considering “ENC” as “highly effective” measure in preventing hearing loss Responsibilities  Involvement in  in the current job  health and  Age (years)  Gender  Ethnicity  Education level  30  39  31  37  PS(degree)  25  Others  36  PS (non-degree)  30  S  35  Canada  32  Caucasian from  <=39  25  female  No  37  male  Yes  41  >=50  Non-managerial  17  >=40 but<50  Managerial  safety activities  30  N.B. Mann-Whitney (for 2 group comparisons) and Kruskal-Wallis (for 3 group comparisons) tests were used to find out difference among subgroups in terms of ratings assigned to ENC. These tests include all the different ratings (1-4) assigned to ENC; however, in this table, proportions across subgroups are shown for “highly effective” rating only just for simplicity.  4.7.5 Other findings There was no statistically significant difference among the subgroups based on job responsibility and involvement in HS activities regarding their perception about HPD. However, the majority of the management (90%) and the group involved in HS activities (95%) believed that NIHL was preventable through the use of HPD (results not shown).  53  4.8 Multivariable analyses 4.8.1 Association between independent variables Only ethnicity and education were found to be significantly associated with each other (p<0.01). Ethnicity was found to be a predictor of risk perception in a few studies (95) (96) (97). So, it was initially included in the MLR model for risk perception; education was not considered for this analysis. The same approach was taken for all the other MLR analyses.  4.8.2 Knowledge of risk 4.8.2.1 Univariate analyses Results on the relationship between knowledge of risk and each independent variable are shown in Table 22-odds ratio (OR) and 95% confidence intervals (95% CI) are provided. Two independent variables were significantly associated with knowledge of risk- involvement in HS activities and ethnicity. People involved in HS activities were more likely to have greater knowledge of risk than those who were not involved in such activities (OR>1). Again, Caucasians from Canada were more likely to be knowledgeable about risk than other people o other ethnicity (OR>1).  54  Table 22: Results of simple logistic regression analyses between knowledge of risk and each independent variable (total number of respondents with good level of knowledge = 46) Independent variables (n) Job responsibility non-management (34) management (12)  Odds Ratio (OR)  95% Confidence Interval (95% CI)  Reference 0.55  Reference 0.23-1.33  Health and safety activities no(10) Reference yes (36) 2.53* Ethnicity other (11) Reference Caucasian from Canada (35) 2.92* Gender female (10) Reference male (36) 1.58 Age <40 years (14) Reference >40 but <50 years (16) 0.98 >=50 years (16) 2.94 Education secondary or less (17) Reference post-secondary (non-degree) (20) 0.53 post-secondary(degree) (9) 0.38 ǂ n=number of respondents with good level of knowledge  Reference 1.01-6.31 Reference 1.20-7.10 Reference 0.61-4.0 Reference 0.38-2.54 0.95-9.10 Reference 0.20-1.40 0.12-1.18  4.8.2.2 Multivariate analysis: Three factors-job responsibility, involvement in health and safety activities and ethnicity remained statistically significant in the final model (Table 23). It is interesting that job responsibility was not significant in the univariate analysis but it turned out to be significant in the multivariable analysis.  Table 23: Results of MLR analyses of knowledge of risk Independent variables Job responsibility non-management management Health and safety activities no yes Ethnicity other Caucasian from Canada  Odds Ratio (OR)  95% Confidence Interval (95% CI)  Reference 0.33*  Reference 0.12-0.91  Reference 2.83*  Reference 1.05-7.60  Reference 3.92*  Reference 1.45-10.6  55  4.8.3 Perception of risk 4.8.3.1 Univariate analyses Results are shown in Table 24 with odds ratio (OR) and 95% confidence intervals (95% CI). Statistically significant association was found between involvement in HS activities and perception of risk. People involved in health and safety activities were more likely to have high perception of risk compared to those who were not involved in such activities (OR>1).  Table 24: Results of simple logistic regression analyses between perception of risk and each independent variable (total number of respondents with high risk perception=74) Independent variables (n) Job responsibility non-management (50) management (24)  Odds Ratio (OR)  95% Confidence Interval (95% CI)  Reference 0.96  Reference 0.32-2.87  Reference 3.62*  Reference 1.25-10.5  Reference 1.57  Reference 0.55-4.45  Reference 0.50  Reference 0.13-1.91  Reference 1.45 1  Reference 0.43-4.86 0.28-3.69  secondary or less (21) Reference post-secondary (non-degree) (34) 1.21 post-secondary(degree) (19) 1.36 ǂ n= number of respondents with high risk perception  Reference 0.37-3.99 0.33-5.55  Health and safety activities no (19) yes (55) Ethnicity other (25) Caucasian from Canada (49) Gender female (21) male (53) Age <40 years (25) >40 but <50 years (31) >=50 years (18) Education  4.8.3.2 Multivariate analysis Only one factor, involvement in health and safety activities, remained statistically significant in the final model suggesting that this factor influences perception of risk (Table 25).  56  Table 25: Results of MLR analyses of perception of risk Independent variables Health and safety activities no yes  Odds Ratio (OR)  95% Confidence Interval (95% CI)  Reference 3.62*  Reference 1.25-10.5  4.8.4 Perception of efficacy of engineered noise control 4.8.4.1 Univariate analyses Results are shown in Table 26. Statistically significant association was found between job responsibility and perception of efficacy of ENC. The result suggest that the management group was more likely to have lower perception of efficacy of ENC compared to the non-management (OR<1). Table 26: Results of simple logistic regression analyses between perception of efficacy of ENC and each independent variable (total number of respondents with high perception of efficacy of ENC=30) Independent variables (n) Job responsibility non-management (25) management (5) Health and safety activities no (7) yes (23) Ethnicity other (13) Caucasian from Canada (17) Gender female (6) male (24) Age <40 years (10) >40 but <50 years (13) >=50 years (7) Education secondary or less (8) post-secondary (non-degree) (15) post-secondary(degree) (7)  Odds Ratio (OR)  95% Confidence Interval (95% CI)  Reference 0.30*  Reference 0.10-0.88  Reference 1.81  Reference 0.67-4.88  Reference 0.62  Reference 0.25-1.53  Reference 1.64  Reference 0.57-4.67  Reference 1.19 0.96  Reference 0.44-3.26 0.30-3.07  Reference 1.32 1.04  Reference 0.47-3.73 0.31-3.49  ǂ n= number of respondents with high perception of efficacy of ENC  57  4.8.4.2 Multivariate analysis Only one factor- job responsibility remained statistically significant in the final model (Table 27).  Table 27: Results of MLR analyses of perception of efficacy of ENC Independent variables Job responsibility non-management management  Odds Ratio (OR)  95% Confidence Interval (95% CI)  Reference 0.3*  Reference 0.10-0.88  4.8.5 Summary Each of all the final MLR models contained only a few (one to three) significant explanatory factors. Nevertheless the above analyses still revealed important findings. It appears that involvement in health and safety activities was significantly associated with the respondents’ knowledge and perception of risk. The direction of this association was positive meaning that those who were involved in such activities were more likely to have high knowledge and perception of risk. Moreover, job responsibility was significantly associated with both knowledge of risk and perception of efficacy of ENC. However, the direction of these relationships was negative: the management was less likely to be knowledgeable about the risk and less likely to have high perception of efficacy of ENC.  58  5. Discussion 5.1Overview Knowledge and perception influence motivation to change and are found to influence preventive behavior. Knowledge and perception of the decision makers and workers on the risks associated with NIHL and prevention measures were suggested to be the barriers to implementation of ENC in workplaces (41). Thus, this study was initiated to investigate the level of 1) knowledge and perception about risk about occupational NIHL and noise exposure and 2) knowledge and perception of efficacy of ENC among the workplace stakeholders. In the following four subsections (5.2.1-5.2.4), an attempt is made to summarize the findings, to provide its interpretations and to signify the importance. In the subsequent sections, some relevant recommendations are made, future research scopes are outlined, and strengths and limitations of this study are mentioned.  5.2 Answering the research questions 5.2.1 Knowledge of risk Overall, the respondents appeared to have moderate level of knowledge- they possessed knowledge of some facts but not about all. For example, they appeared to be knowledgeable about the health effects of noise exposure, development of NIHL, early signs of NIHL, and about one of the limitations of HPD (e.g., tightness of fit). However, there appeared to be very poor knowledge among the respondents about the level of noise that may pose a risk to their hearing ability and the reduction in effectiveness of HPD due to not wearing HPD even for a short duration. The knowledge level, although found to be generally moderate in all subgroups, was relatively better among the non-management group and those involved in HS activities compared to their counterparts (however, the differences were not statistically significant in most cases). After taking into account the effects of age, gender, ethnicity, education and involvement in HS activities, job responsibility was found to have an association with knowledge of risk. Management was less likely to have knowledge about the risk compared to its counterpart. On the other hand, after taking into account the effects of age, gender, ethnicity, education and job responsibility, involvement in HS activities was found to have an association with knowledge of 59  risk. The group involved in HS activities was more likely to have knowledge about risk compared to its counterpart. Literature on knowledge of occupational noise exposure and/or NIHL is limited. Moreover, studies on the above topic (knowledge of occupational noise exposure and/or NIHL) involving decision makers as subjects are non-existent. Apart from the pilot study (41), a few studies (67)(66)(24)(64)(65) were found which reported some relevant information. The results of those studies seem to be comparable to those of ours as those studies measured awareness about risk in almost the same way as we did; however, our study carried out a more detailed investigation of knowledge of risk than those (we measured knowledge on different aspects: noise exposure, health effects (auditory (short term and long term) and non-auditory), early signs, limitations of HPD). Moreover, the study subjects of the most of those studies are somewhat similar to ours in the sense that respondents of most of those studies belonged to manufacturing industry (except one with firefighters (24)) where noise is likely to be present (firefighters are also exposed to noise which is usually of high intensity, short duration and intermittent (24)) and were males. However, the study subjects differed from ours in job responsibility and in geographical location. Nevertheless, these studies provide some ideas about the state of knowledge of risks about occupational noise and hearing loss. Some of the studies’ findings concurred with ours (67)(66)(24) whereas some did not (64)(65). In general, earlier studies (published in mid 70’s and early 90’s) reported poor awareness (64)(65) and recent studies (published after 2000) reported high awareness (67)(66)(24) among the study subjects. This difference may be assumed to be due to time- people are now more aware of health than in the past. Although differences may also be attributed to difference in populations (e.g. in terms of education) or difference in regions (developed countries vs. developing or least developed countries), looking at those studies, this does not seem to be the case since studies in a wide variety of respondents reached almost the same conclusions. The findings of the studies are described in the rest of this paragraph. A study (method: questionnaire survey; published: 2004) among workers (n=313; male=89%) in the manufacturing industry (fibreglass product industry sample=154, metal product industry sample=159; region: Sweden) found that the majority (95%) of the workers were aware that loud noise could damage hearing (67). Another study (method: questionnaire; published: 2005) among workers (n=116; male=94%) in a steel rolling mill 60  (region: Nigeria) found that the majority (93%) were aware that exposure to loud noise could cause deafness (66). Similar finding was reported in another study (method: focus group) involving firefighters (n=24; male: 92%; white: 88%; region: Michigan, USA)- the majority knew that loud noise caused hearing loss (no numbers, percentages, or figures regarding results were reported in this study) (24). These findings are concurrent with that of ours. The pilot study (41), conducted in almost the same population as ours (industry: food and beverage industry in BC, n=55; workers=21, managers=23, maintenance personnel=11), reported findings which are similar to ours: workers were generally aware of the link between noise exposure and hearing loss and some were aware of non-auditory effects (stress, hypertension etc.). However, a few studies published in the past (early 90s and mid 70s) reported contradictory findings. A study among factory workers (n=442 noise exposed; 82 non-noise exposed; region: Malaysia; published in 1993) found that only a small fraction (35.5%) of the noise exposed workers were aware of the possibility of developing NIHL due to exposure to excessive noise (64). Another study (method: questionnaire; published in 1976) in boiler making industry concluded that there was a lack of knowledge of noise hazard (65). The majority of our respondents knew “loud” noise was harmful to their hearing but their unawareness about the maximum level of noise (as specified in the regulations) creates doubt about their understanding of “loud” noise. It might be the case that our study respondents’ interpretation of “loud noise” was greater than the regulatory limit (85 dBA). In other words, the respondents in our study may not be good at discriminating hazardous level of noise around the regulatory limit. However, with the current data, it is not possible to ascertain whether this is the fact. A study (method: questionnaire) in beverage industry ( and also in textile, apparel, printing, wood industries) revealed that workers (n=434; textile:158,textile and apparel: 156, printing and label production: 18; high pressure laminating production: 58; beverage production: 44; male: 71%; region: Portugal) exposed to high level of noise (greater than 85 dBA) did not consider that their workplaces were hazardous (34) even though they appeared to know that loud noise was hazardous to their hearing. The study population was somewhat similar to ours with respect to industry, presence of noise in the workplaces and gender but was dissimilar with respect to education (about 99% had either secondary level of education or less in the above study) and job  61  responsibility (all were workers in the above study). Thus, this study may not be a strong proof for our assumption; nevertheless, it still provides some indication about the state. The two key decision-making subgroups, the management and the group involved in HS activities, had very poor knowledge about the maximum noise level that a worker could be exposed to (less than one-fourth of the management and approximately one-third of the group involved in HS activities were aware of this fact). If the decision makers are not aware about what level of noise is hazardous, it will certainly be difficult for them to decide whether their workers are at risk. If they do not know that their workers are exposed to a risk, they may not search for or undertake any preventive initiatives since knowledge is identified as a barrier to change(42). The lack of knowledge among workers reported in this study is also of importance as the pilot study done previously (41) indicated that the management relied on workers for identification of hazards. If workers do not have knowledge about the risk, such as, what level of noise is hazardous, it will be difficult for them to identify it. As HPD’s effectiveness is highly dependent on the intermittency of use (37) (36), the widespread lack of knowledge among the respondents as revealed in this study about protection lost due to not wearing HPD for the entire work-shift is a matter of concern (only about onetwentieth of the respondents were aware of this fact). As studies mentioned about the high level of discomfort associated with HPD use (31) (32) (38)(4), it may be the case that the workers of this study might have been using HPD only intermittently. This may be true since several studies reported under-use of HPD by workers. A study in the construction industry in the US Midwest reported that workers (n=400; fitters, carpenters and operating engineers) did not use HPD during the entire duration of noise exposure (fitters and carpenters used HPD 12%-40% of time they were exposed to noise whereas, the operating engineers used around 50% of the time) (98). The industry studied (construction industry) was a noisy industry and the subjects were from North America; thus, the sample was a bit similar to ours in many aspects (noise exposure, region and demographical characteristics: male = 94%, white = 86%). Moreover, Other studies reported only a small proportion of workers using HPD all the time they were exposed to noise (5%, 28% and around 30% of workers used HPD all time in studies (64) (66) (34)respectively). If decision makers are not aware of this situation, they may be complacent that they are protecting the workers by prescribing HPD- while in reality- they are not. 62  In general, the respondents did not have enough knowledge of risk about noise exposure and NIHL.  5.2.2 Perception of risk The respondents’ perception of risk appeared to be of moderate level. They seemed to perceive that NIHL could cause great negative impacts on life. They, more or less, perceived that the workers at their workplaces may be at risk for NIHL. In addition, they considered NIHL to be of lower level of concern than some other diseases/health problems. The group involved in HS activities showed moderate level of risk perception and their perception was slightly higher than their counterpart (although the differences were not significant in most cases). Both groups appeared to have lower level of concern for NIHL (only about one-fifth of each group considered NIHL to be diseases of high concern). However, the group involved in HS activities perceived the negative consequences of NIHL on life more than their counterparts (the proportion in the HS group, who perceived the negative consequences of NIHL on life, was more than their counterparts). In addition, this group involved in HS activities seems to perceive that their workers’ chance of developing NIHL may be low. After taking into account the effects of age, gender, ethnicity, education and job responsibility, involvement in HS activities was found to be significantly associated with perception of risk- those who were involved in such activities were more likely to have high risk perception compared to those who were not involved in such activities. The management group showed lower risk perception compared to the non-management group (although the difference was not significant in most cases) and their risk perception, was in general, moderate. For example, the level of concern for NIHL appeared to be much lower among the management group compared to the non-management category (only about one-tenth of the management considered NIHL to be the most concerning problem but this proportion was double for the non-management). Moreover, this group (less than half) had lower perception about a worker’s chance of developing NIHL in their workplaces than their counterpart (about two-third). The management seemed to perceive the negative consequences of NIHL on life, however, this group showed slightly lower perception in this regard than its counterpart. After 63  controlling for the effects of age, gender, ethnicity, education and involvement in HS activities, job responsibility was not found to be associated with perception of risk. Apart from the pilot study (41), a few studies were found that reported findings on risk perception of occupational noise. Though the subjects of those studies were different (in terms of occupation, workplaces etc.), they arrived at similar findings as our study. The Swedish study involved a sample of workers (majority: males) in manufacturing industry and measured perception almost the same way as we did (item: I think it would be big problem if I lost my hearing). It reported that the majority (90%) of respondents considered hearing loss to be a serious problem (67).Our study corroborated their findings. However, this study didn’t measure how NIHL would be rated among other health problems. The study on firefighters on noise exposure and hearing loss (99) showed that fire fighters thought that noise and NIHL were major occupational health problems; however when asked to name the major problems in terms of mortality and workdays lost, NIHL turned out to be a low priority hazard compared to other problems since this did not result in mortality or lost workdays. The firefighters even implied that NIHL was a risk they were willing to take. Although our sample is much different from that study in terms of occupational culture (risk taking behaviour is thought to be a culture of firefighting occupation (24)), the respondents in our study implied similar notion, i.e., NIHL was a less concerning hazard than other problems. The pilot study (41), conducted in almost the same population, revealed that noise was a low priority among other issues (accidents, sanitation, product quality, absenteeism etc.). The lower level of concern about NIHL among the respondents compared to other health problems/diseases can be explained by the fact that risk perception is influenced by a lot of factors including dread, control, or extent of damage/severity of consequences (100). Thus, the lower ranking of NIHL among a given set of hazards or diseases may be a reflection of the relative contributions of these factors. Risk perception is influenced by dread (100), and cancer and memory loss diseases are viewed as dreadful diseases. Moreover, perception of risk is thought to be higher for events that can have catastrophic effects or events on which people have little control (100). Thus, ratings assigned by the respondents to chemical burns and accidents could be explained by this.  64  Risk perception is the subjective assessment of the probability of a specified type of accident happening and how concerned we are with the consequences (100). Perception of risk includes evaluations of the probability as well as the consequences of a negative outcome (100). Thus, evaluation of risk perception should include two components: probability and consequences. We read the results on the consequences: level of concern for NIHL and its effects on life. Now let us look at the results on the other aspect- the perception of probability. The majority (around four-fifth) felt that their hearing was protected. This perception appeared reasonable for the management group (greater than four-fifth in this group felt that their hearing was protected) who usually do not encounter noise in their day-to-day activities. However, it is surprising that the majority of the respondents potentially at risk (i.e. the non-management) felt this way as well (about four-fifth of the non-management). But, when asked about workers’ chance of developing NIHL in their respective workplaces, the majority of this group appeared to imply that it was not low (about two-third of the non-management). The results are contradictory—they appeared to think that there was a chance of developing NIHL in their companies but their chance of developing it was low. This finding may suggest the presence of a phenomenon known as optimistic bias (100)- the tendency to claim that one is less at risk than their peers (101). Acceptance of personal vulnerability is an important aspect of progress towards precaution adoption (102). Optimistic bias is, thus, suggested as a barrier to action (102). Optimistic bias decreases people’s risk perception. Since high-perceived risk could engender greater concern about a health hazard (53) and as greater concern about a health problem (e.g., NIHL, skin cancer, and respiratory diseases) is a motivational factor in taking preventive actions (54), the above result is meaningful. If the people in the at-risk group consider that they are not at risk, the possibility of them being concerned for themselves is low. If they do not feel concerned, they may not even have the motivation to report the hazard to the appropriate authority in their workplaces. Although this study did not carry out any on-site measurement of employees’ exposure to noise, the noise levels in the majority of the companies may well be above the regulatory limit since the majority of those companies have HCP (19 out of 22 companies) and HCP is required when noise level exceeds the regulatory limit. However, only a small proportion of the respondents in the decision making subgroups (the management and the group involved in HS 65  activities) appeared to perceive that their workers were at risk for NIHL (not all respondents in these groups perceived this risk and only about half understood). If these groups do not think that their workers are potentially at risk, it is less likely that they will be motivated to look for prevention measures to put in place. In conclusion, the respondents did not show high risk perception.  5.2.3 Knowledge about engineered noise control Knowledge of ENC appeared to be very poor among the respondents. Overall, very few respondents could cite concrete examples, could give ideas about ENC or were aware of OHS regulations on noise which has a noise control component as the first priority. The decisionmaking subgroups seemed to have poor knowledge about ENC since they showed poor awareness about OHS regulations on noise (less than half were aware of OHS regulations). Only a small proportion of the respondents would consider approaching acoustical consultants to gain information about suitable ENC for their workplaces. Most popular sources for information seem to be the internet and WorkSafeBC. A review of literature revealed this to be the first study to particularly investigate knowledge about ENC. Thus, it is difficult to conclude how our findings compare with existing knowledge. However, a few studies revealed relevant findings that are concurrent with ours. The pilot (41)study which was conducted in a similar sample revealed similar findings: weak understanding of ENC among decision makers and also workers. The study in steel rolling mill reported information on knowledge about prevention measure (66). It revealed that knowledge about ENC among workers was poor (2% were aware of isolation of noisy machines as a prevention measure) but knowledge of other prevention measures was better (98%, 55% were aware about HPD, training of workers on hazards of noise). Moreover, a study (region: Washington State in US) on NIHL in the workplaces (n=10) in an industry (foundry) with high rates of NIHL claims revealed that no interviewed management representatives possessed a copy of the regulations, or had read them (30). Only a few respondents (n=3) answered the knowledge question correctly. The poor response on the knowledge question may also point to another issue- whether the knowledge of ENC question was well-designed in our questionnaire. The respondents might have skipped this 66  question because it was open ended; however, looking at the responses of another open-ended question in this study (“what language do you speak at home?”), this does not appear to be the case. One may again argue that use of unfamiliar terms such as “engineered noise control” might have confused the respondents, but this term was explained at the beginning of the ENC section in the questionnaire. Moreover, the pilot test provided no such indication of lack of clarity. The large number of missing values, on the other hand, may just point to the overall state of poor knowledge among the respondents—they might have skipped this question because they did not have an answer. The lack of knowledge about ENC among the respondents can also be partially verified by the gathered data. It was found that the majority of the respondents used HPD and had their hearing tested (slightly greater than half of the respondents used HPD and about nine-tenth of the respondents had their hearing tested). Moreover, almost all said that NIHL was preventable through HPD and that hearing tests gave advance warning of NIHL. In other words, there appears to be high awareness about HPD and hearing tests. However, when asked whether there was any ENC in their workplace, around half said that they did not know. This may point to a lack of knowledge of ENC. However, a similar proportion said yes and a smaller proportion said no. There were conflicting answers from the respondents within the same company and thus, we cannot say for sure whether their answers are proof of their knowledge about ENC. Since the respondents showed very poor awareness with OHS regulations on noise (which has a section on noise control), it is likely that the awareness about ENC was poor among the respondents. Moreover, the majority (two-third) of the respondents had a belief that ENC was complex and difficult; but, in fact, ENC can be as simple as a thick carpet or a heavy curtain. A lack of knowledge about ENC might have formed this notion. OHS regulations on noise lay out all the steps including ENC necessary to prevent NIHL. Since there was poor awareness about OHS regulation on noise among the group involved in HS activities and the management (two-fifth of each group were aware), it is not unreasonable to assume an incomplete implementation of HCP in the workplaces. This may be true since the pilot study (41) (n=8 companies with HCP) revealed that HCPs were only partially implemented in those companies. Moreover, the study in Washington State in an industry with high rates of  67  NIHL claims revealed that all inspected companies (n=10) were out of compliance with hearing conservation regulations (30). Risk reduction behavior is supposed to be influenced by knowledge of prevention measure (46,57). People need to know what prevention measures are available; if they are not aware of a particular measure, it stands to reason that it will not be on their list of potential choices. The poor awareness about ENC revealed by this study is, thus, a matter of concern. If the management and those involved in HS activities are not aware of ENC, ENC may not even be on their list of potential prevention measures. Moreover, people engaged in HS activities had poor knowledge about ENC but they were pointed out as the preferred sources of information on ENC. If these people are not knowledgeable, they obviously cannot guide the management or other groups who seek advice on prevention measures, such as, ENC. To sum up, we conclude that the knowledge of ENC was poor among the study respondents.  5.2.4 Perception of efficacy of engineered noise control The respondents’ perception of efficacy of ENC in preventing NIHL was very poor. They considered it less effective than HPD, education of employees, and annual hearing tests. Both the management and the group involved in HS activities had poor perception of efficacy of ENC (only one-fifth of the management and two-fifth of the group involved in HS activities considered ENC to be highly effective). After adjusting for the effects of age, gender, ethnicity, education and involvement in HS activities, job responsibility was found to be associated with perception of efficacy of ENC- the management was less likely to have high perception of efficacy of ENC compared to the non-management. Involvement in HS activities was not, however, associated with perception of efficacy after adjusting for age, gender, ethnicity, education and job responsibility. No previous study focused particularly on the perception of engineered noise control. Only three studies revealed some information regarding ENC, but none of these investigated respondents’ perception of efficacy regarding ENC (39) (33) (40). However, high perception of effectiveness of HPD revealed in this study is concurrent with other studies. The pilot study (41)reported that there was a belief that the hazard of noise was “adequately managed” by HPD 68  and hearing tests; HPD was described as a sufficient protection against noise and most of the respondents thought it to be the best measure. The study on Swedish manufacturing workers (67) and Michigan firefighters (24) revealed that the majority believed that NIHL was preventable through HPD. Perception of effectiveness of prevention measures plays an important role in people’s decision about which to choose (57) (58). The findings of this study, therefore, are of importance. If the management and the group involved in HS activities do not view ENC to be highly effective in preventing NIHL, it may not be their highest priority while making decisions about preventive actions against NIHL. Since the pilot study revealed that the management wanted the workers to recommend potential solutions, it is important that workers also have high perception about ENC’s effectiveness. HPD was thought to be much more effective than ENC by the respondents although ENC is considered to be the most effective measure to prevent NIHL by experts. ENC received even lower rating (in terms of the perceived level of effectiveness) than education and audiometric tests. The low rating of ENC may, partly, be a reflection of the respondents’ lack awareness of ENC. If they do not know what ENC is, it stands to reason that they will not have high regards for it. Almost all (greater than or equal to 90%) of the management and HS respondents believed that NIHL was preventable through HPD. It is possible that they might have a notion that their workers were already protected from NIHL. Why would they consider searching for other prevention measure when they believed that the current one was providing enough protection? In conclusion, the respondents had very low perception of efficacy of ENC.  The important findings emerging from this study are summarized below: The respondents seemed to have a lack knowledge on important areas, such as, limitations of HPD and harmful level of noise. There seemed to be a lack of understanding of ENC among the respondents. The respondents considered it to be less effective than HPD, hearing tests and education. In fact, HPDs seemed to be very highly regarded by the respondents.  69  With respect to subgroups, both the management and HS groups lacked knowledge about important facts. Both of these groups had poor knowledge and perception of efficacy of ENC and perceived that their workers might not be at risk for NIHL.  5.3 Recommendations Health education is suggested to be an important tool in the prevention of occupational diseases (45). Thus, an educational campaign should be undertaken to educate workplace stakeholders about NIHL and ENC. The campaign should focus on educating workplace stakeholders about ENC and its effectiveness. They should also be made aware of the place of HPD in the hierarchy of control measures. Moreover, they also need to be educated about the limitations of HPD and what impact these limitations (tightness of fit and protection lost due to not wearing HPD for the entire shift) have on the effectiveness of HPD. They should also be educated about the effectiveness of hearing tests. The respondents in this study thought that audiometric test (AT) was a better measure than ENC. Moreover, they believed that AT gave advance warning of hearing loss. But researchers argue that these tests cannot detect hearing loss at an early stage (32). Additional recommendations regarding educational campaign are that workplace stakeholders should be informed about what level of noise is hazardous to hearing. Moreover, they should be educated on how to subjectively judge the level of noise. This may be useful when noise measuring equipment is not available right away. Training campaigns should also focus on educating the workplace stakeholders about NIHL-how it develops and the importance of taking precautions (since NIHL is irreversible and early signs are not easily noticeable, it is important to take early actions). Particularly, the decision makers should be aware about how NIHL can affect both the workers in respect to the loss of quality of life and the organization in respect to financial loss due to accepted claims. Since the study pointed out that the management had poor knowledge and perception about ENC and poor knowledge and perception about risks regarding NIHL, this group should be particularly targeted for educational campaigns. In another study, similar recommendations were made “the need for more education and motivation of senior managers as the priority in improving standards of hearing conservation and noise control” (33). Since management controls 70  the resources, their knowledge and perceptions are utterly important. Other researchers also implied similar opinion- education (44), training (103) (104) and support (44) (103)of the management is important in maintaining health and safety at workplaces. The previous pilot study indicated that the management depended on workers identifying hazards and offering possible solutions and reporting those to them. It is unlikely that the management will trust workers’ recommendation unless they understand the importance of prevention, are knowledgeable about the best solution, and believe in its effectiveness. Our study also pointed out the need for educating the group involved in health and safety, since the results of this study indicated that the state of knowledge of risk and knowledge and perception of ENC was also poor in this group. This group is partly responsible for workplace health and safety. Moreover, HS professional and JHSC members were identified as two popular sources of information regarding ENC and were considered to be responsible for identifying a workplace hazard by the majority of the respondents. Thus, it is important that educational intervention is directed towards this group as well. Since the majority of the respondents chose Internet and WorkSafeBC as their sources of information on ENC, policy makers should focus on developing online information sources and special brochures on ENC and make them available through WorkSafeBC. These resources should be designed, in such a way that it can provide easy to understand but thorough knowledge of ENC, such as, what it is, how they work, benefits, price range, installation complexity, consultants who can provide guidance on which ENC to implement, and stores that sell ENC. Information on cost should be provided, as cost appears to be an important factor to the respondents in making decisions about the implementation of ENC. Efforts should be taken to make the HS people aware of these information sources so that they can learn about ENC and provide guidance to those who seek advice regarding prevention measures. Easy access to information may clear away subjects’ confusion about ENC. We recommend setting up of a specialized branch within WorkSafeBC which will provide guidance and information on ENC to those asking for help. A similar attempt was taken by WorkSafeBC a long while ago (Noise Control Compliance Plan in 1980), but it was abandoned later. We recommend creation of a similar branch.  71  Since regulatory context was considered to be a barrier to the implementation of ENC in the pilot study, we recommend a slight change in regulations: companies with noise levels exceeding the permissible level should be required to contact the specialized branch of WorkSafeBC. Moreover, WorkSafeBC should also offer educational workshop on ENC and NIHL and require the attendance of JHSC members, health and safety personnel and the management of such workplaces at these workshops. It is our opinion that there should be a reward system for companies that implement ENC. According to Green, a desired behavior will not sustain unless it is strengthened by reinforcements, for example, rewards (48). According to us, the rewards for adopting ENC may come in inexpensive ways. The regulatory agency or the government may hold a symposium to confer awards, such as, certificates lauding these companies’ endeavors. This type of activities carried out by the government or the regulatory agency will encourage other companies to adopt ENC. In Singapore, the Ministry of Manpower, held such conferences and provided awards to companies that controlled noise using ENC (26) and over the years, it was shown that more companies implemented ENC. We suggest that the government considers making the cost of ENC tax deductible or the regulatory agency considers reduction in the assessment rate for companies implementing ENC. Another way of promoting ENC will be to provide examples about what other companies are doing- as suggested by another study (39). This may have great effects – if people see the proof that ENC is effective, they are likely to be encouraged to adopt it. Some other recommendations coming out of this study are briefly mentioned here: One way to improve occupational health and safety situations in workplaces is by enforcing laws by regulatory agency (105). A study in Oregon showed that increased regulatory enforcement (e.g.safety inspections in areas known to be especially problematic, penalties against employers that violated existing safety and health regulations ) along with government initiatives to encourage management and labor to improve workplace safety resulted in a decrease in NIHL claims rate- there was a 600% increase in the number of citations issued by the regulatory agency against employers for safety violation after the enactment of law to augment enforcement (106). Better enforcement is needed from WorkSafeBC. It should routinely visit workplaces to check for records of noise measurement and implementation of other components 72  of HCP. As this study pointed out poor awareness among the decision-makers about OHS regulations on noise, it is possible that they might be unaware about HCP, and thus, it is likely that components of HCP, such as, noise measurement, may be missing. But, noise measurement is an important step to identify whether the workers are at risk. Moreover, WorkSafeBC should also make labeling of the noise level of machines mandatory for companies that produce machines so that workplaces can make informed decisions about choosing a low-noise machine. More importantly, WorkSafeBC should change its impression about its focus regarding NIHL prevention. We searched its web page on “NIHL Prevention” under the “Safety at Work (by topic)”, but, looking at this page, it appears that WorkSafeBC’s focus is on HPD and audiometric tests rather than ENC. This page contains information on various topics except ENC. Information on HPD and AT seems more readily accessible than ENC, since these two are shown on the first page. Information on ENC is located in a page that is far behind the other pages. There is a lot of information on HPD (types of HPD, statistics on HPD usage by various industry, working group, etc.) and audiometric tests (AT authorization, good booth, information on records of these tests, etc.) but information on ENC seem to be smaller compared to AT and HPD. All these may give a lay person an idea that WorkSafeBC gives more importance on HPD and AT rather than on ENC. Thus, more online information should be provided on ENC, and this should be made easily accessible. Moreover, during routine inspections, WorkSafeBC should emphasize the need for implementation of ENC to the decision makers. Above all, researchers should put their attention to the promotion of ENC. It appears that HPD has been a topic of more extensive research compared to ENC. Research should guide policy. In the absence of research on this topic, new and effective recommendations will not emerge. The amount of HPD research done may give a lay person an idea that HPD is a very important issue and that ENC is probably less important than HPD. If researchers are focused on HPD, how can we expect to see a better picture among the lay persons, such as, workplace stakeholders?  73  5.4 Future research It was not possible to know whether the companies had ENC or had high noise levels. So, in future, a field investigation can be carried out to perform an inventory of ENC and measurements of noise for such a study. The study can be replicated in a randomly selected group of respondents with a revised questionnaire. The revised questionnaire may include questions about the respondents’ idea of “loudness”. Respondents can be asked if they would consider the presence of TTS or tinnitus to be concerning phenomena since some researchers noted that TTS was not viewed as a matter of concern by people (34). If possible, an interview method can be used rather than the questionnaire survey to have an in-depth understanding of the respondents’ knowledge of ENC. By identifying predisposing factors, this study partly completed the last phase of Precede aspect of Green’s Precede/Proceed model. To make the phase 4 complete, the researcher recommends future studies to investigate two other factors, namely enabling and reinforcing factors, since behaviour is caused by the “collective influence of these three types of factors” (48). After identifying all three types of factors, the next step should be to set priorities among and within the categories and high priority factors should be targeted for intervention. This will make the phase 4 complete. Then, the subsequent phases, phase 5 (assessment of organizational resources, policies and capabilities to support recommendation) and phases 6-9 (implementation and evaluations of interventions), should be carried out. After implementing the interventions in a number of companies in the food products manufacturing industry, outcome should be evaluated and the results should guide policymakers in formulating strategies regarding the implementation of ENC and thereby preventing NIHL.  5.5 Strengths and limitations The majority of the (n=78, 85%) respondents worked in companies with hearing conservation programs; in other words-the majority of respondents belong to companies with apparently high noise levels. Thus, the results may not be generalizable to the entire industry. However, the responses of the study sample are still considered useful—the results of this study may help formulate strategies to protect the workers potentially at risk of NIHL. 74  Since the respondents were chosen using convenience sampling, there may have been a selection bias. The contact person might have given the questionnaires to those who were interested in the survey, and thus, there may have been volunteer bias present. However, we think that the results still provide useful insights. It is our assumption that people who are conscious about health will be more interested to participate in a survey like this than those who are not. Thus, we think that this study has captured the responses from health conscious group of people. If this group has a poor state of knowledge and perception, it is likely that the responses from those who are not conscious about heath would have been worse. Response rate for individuals was 32.5 %. A scarcity of questionnaire survey research on risk perception and knowledge on occupational noise and ENC and unavailability of response rate data from such studies made it difficult for us to compare our response rate to that of other studies. However, response rates for mail-out questionnaire surveys tend to be poor; without any offer of incentive, the response rate may often be no more than 20%. Even with incentives and follow-up phone calls, the response rates for such surveys can be quite low (107). The range of response rates for mail-out questionnaire survey tends to fall between 10% to 50% (90). Considering these, the response rate of this study can be considered good. The sample size (total respondents) seemed moderate (n=92); one other study on knowledge and attitude on occupational noise had a sample of 116 workers (66). It is assumed that ENC is not in place in the participating companies and noise level is high in these companies. As no field investigation was done, this assumption cannot be verified. However, a study in the Washington State found that noise levels in workplaces in an industry (foundry) with high rate of NIHL claims routinely exceeded 85 dBA (30) and that all workplaces (n=10) were out of compliance with HCP. Moreover, none of those evaluated companies had made any substantial past effort or future plans to reduce noise levels (30). Since the majority of companies (86%) and the respondents (85%) of our study are from companies with HCP, those above assumptions appear to be reasonable. The study carried out a detailed investigation on perception and knowledge of noise risk and ENC. It gathered data on a number of aspects of NIHL, ON and ENC. Moreover, it is unique in the sense that according to our literature review, no other study focused particularly on knowledge and perception on engineered noise control among decision makers. 75  The questionnaire used for this study seems to have fair reliability. It was developed and reviewed by experts; so it seems to have construct validity.  76  6. Conclusions The study reports perception and knowledge about occupational NIHL and ENC among decision makers and workers in some food products manufacturing companies. Overall, it appears that the respondents had very good perception of the negative consequences of NIHL on life. However, they considered NIHL to be of lower concern compared to other health effects. Respondents were knowledgeable about the effects of noise exposure on their health and also aware of the insidious onset and slow developmental pace of NIHL. However, they had poor knowledge about the harmful level of noise and the limitations of HPD. Respondents had poor knowledge about ENC as well. There was very poor perception among them about the efficacy of ENC to prevent NIHL. Compared to HPD, education of employees and annual hearing tests, ENC was thought to be less effective by the respondents. Hearing protection devices were thought to be the most effective measures. The management showed poorer knowledge and lower perception in most cases compared to its counterpart. Most of the companies in the study were from WorkSafeBC’s list of companies with hearing conservation programs, and as such, it is not reasonable to make a generalization of the findings for the entire industry. As this study appears to be the first of its kind, the results should be validated by further studies in future.  77  References (1) Nelson DI, Nelson RY, Concha-Barrientos M, Fingerhut M. The global burden of occupational noise-induced hearing loss. Am.J.Ind.Med. 2005;48(6):446-458. (2) Verbeek JH, Kateman E, Morata TC, Dreschler W, Sorgdrager B. Interventions to prevent occupational noise induced hearing loss. Cochrane Database Syst Rev. 2009 Jul 8;3. (3) McReynolds MC. Noise-induced hearing loss. Air Med.J. 2005;24(2):73-78. (4) Fausti SA, Wilmington DJ, Helt PV, Helt WJ, Konrad-Martin D. 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Thousand Oaks, Calif.,USA: Sage publications Inc.; 1995.  85  Appendices Appendix A: Ethics approval letter  86  Appendix B: Invitation letter  School of Environmental Health 3rd floor-2206 East Mall Vancouver, B.C. Canada V6T 1Z3 www.soeh.ubc.ca Tel: (604)822-9595 Date Name of the contact person Designation Company Address Re: A study on noise at workplaces and engineered noise control Dear Mr. < name >, We would like to invite your company to participate in a research study on noise at workplace and engineered noise controls. Through this study, we are trying to understand how we can better reduce noise at workplaces. Your company was randomly chosen through BC Manufacturers’ Directory or Yellow Pages. Participation is simple. If you agree, we will send you a package of questionnaires, and ask you to distribute these to • The members of your company’s joint health and safety committee • A few other managers (preferably head of maintenance, head of production, financial officer) who are not on that committee • Two production workers who are not on that committee. The participants complete the questionnaire (it takes no more than 20 minutes) and then mail it back to us. A postage paid return envelope is attached to each questionnaire. There is no cost to the participant, and everyone who is asked to participate can have their name entered in a draw for an Apple iPod (value $300). However, providing names or contact information is optional. All the answers are kept confidential. Nobody will be able to identify any of the participants. The information provided will be grouped with other participants. Hearing loss caused from noise exposure at workplaces resulted in several hundred claims accepted by WorkSafeBC in the year 2006 alone. This not only causes significant negative 87  impacts on the lives of the sufferers but also incurs huge financial loss to employers. Research shows that reducing noise (i.e. using engineered noise control) shows the best promise to prevent hearing loss. However, in most workplaces engineered noise controls remain underutilized, while the incidence of noise induced hearing loss remains high indicating the need for a new approach. This study is very important as it will help formulate strategies to create a safe and healthy working environment free of hazardous noise. We hope you will help us in our effort to create a noise-free working environment .Looking forward to hearing from you soon. If you have any question, please email at mnahid@interchange.ubc.ca, or call (604)827-4017. Sincerely Musarrat Nahid, M.Sc. candidate, School of Environmental Health University of British Columbia  88  Appendix C: Instruction sheet  Instructions for distributing the questionnaires: Thank you for agreeing to participate in our survey. Please follow the instructions below carefully: •  Please give one questionnaire to each of these following: All the members of your company’s joint health and safety committee A senior production manager who is NOT on that committee A senior maintenance manager who is NOT on that committee A senior financial officer who is NOT on that committee Two production workers who are NOT on that committee and selected as follows: To ensure a random selection, please select two workers whose birthdays are closest to the date you deliver the questionnaire.  If you have any questions about who to select, please call at (604)822-6777 or email at mnahid@interchange.ubc.ca  89  Appendix D: Request for redistribution of the questionnaire  School of Environmental Health 3rd floor-2206 East Mall Vancouver, B.C. Canada V6T 1Z3 www.soeh.ubc.ca Tel: (604)822-9595 Date Name of the contact person Designation Company Address Re: A study on noise at workplaces and engineered noise control Dear Mr. < name >, I am an M. Sc. student at the School of Environmental Health in the University of British Columbia (UBC). I contacted you some time ago about my thesis study on noise at workplace and engineered noise controls. Through this study, we are trying to understand how we can better reduce noise at workplaces. You kindly offered your support for this study and I sent you a package of questionnaires after our discussion over the phone. I am hoping to get back as many questionnaires as possible to maximize the response rate which is very important for the successful completion of my thesis. For that reason, right now I am again sending questionnaires to the companies that I recruited. My aim is to reach out to those who probably couldn’t manage time to complete my questionnaires last time. I would greatly appreciate if you could distribute these questionnaires to the same persons you delivered the questionnaires last time but who did not have a chance to complete those. I hope this will allow them an opportunity to complete the questionnaires this time. Please note that the questionnaires must be given to the same persons. So contacting new persons is not necessary. Participation is simple. Please follow the Instructions for distributing the questionnaire attached with this letter. The participants complete the questionnaire (it takes no more than 15 minutes) and then mail it back to us. A postage paid return envelope is attached to each questionnaire.  90  There is no cost to the participant, and everyone who is asked to participate can have their name entered in a draw for an Apple iPod (value $300). However, providing names or contact information is optional. All the answers are kept confidential. Nobody will be able to identify any of the participants. The information provided will be grouped with other participants. Hearing loss caused from noise exposure at workplaces resulted in several hundred claims accepted by WorkSafeBC in the year 2006 alone. This not only causes significant negative impacts on the lives of the sufferers but also incurs huge financial loss to employers. Research shows that reducing noise (i.e. using engineered noise control) shows the best promise to prevent hearing loss. However, in most workplaces engineered noise controls remain underutilized, while the incidence of noise induced hearing loss remains high indicating the need for a new approach. This study is very important as it will help formulate strategies to create a safe and healthy working environment free of hazardous noise. I greatly appreciate your kind support for this research. I hope you will help us in our effort to create a noise-free working environment. If you have any question, please email at mnahid@interchange.ubc.ca, or call (604)827-4017. Sincerely Musarrat Nahid, M.Sc. candidate, School of Environmental Health University of British Columbia  91  Appendix E: Questionnaire  92  93  94  95  96  97  98  99  100  101  102  103  104  105  106  107  108  109  110  111  Appendix F: Classification of questions Table: classification of questions into different categories Category  Sub-category  Risk perception  Question number 1,page5 5,page6 7,page6 10,page6 11,page6 1,page 9 2,page 9 9, page 6 10,page 2 1,page 8  Knowledge of risk  2, page 10 2, page 5 3, page 5 6,page6 1, page 10 3, page 10 12, page 6  Knowledge of ENC  Perception of efficacy of ENC Other perceptions about ENC  perception of feasibility perception of cost as barriers perception of other benefits  description Perception of the impacts of NIHL on life Perception of the impacts of NIHL on life Perception of the impacts of NIHL on life Perception of the impacts of NIHL on life Perception of the impacts of NIHL on life perception of the level of concern for NIHL compared to other health effects perception of the level of concern for NIHL compared to other diseases perception of worker’s chance of NIHL perception of own hearing knowledge of the level of noise that can cause damage to hearing knowledge that temporary loss of hearing and tinnitus may occur with exposure to noise for some time for reliability check---knowledge that temporary loss of hearing may occur with exposure to noise for some time knowledge of some other effects (non-auditory) of noise exposure knowledge of risk of exposure to loud noise knowledge of some other effects (non-auditory) of noise exposure knowledge of other causes of hearing loss knowledge that the progression of NIHL is difficult to notice knowledge of risk of exposure to loud noise knowledge that NIHL develops slowly Knowledge of limitation of HPD Knowledge of limitation of HPD knowledge of an early sign of hearing loss what ENC is  13,page7 14, page7 1, page 11 4, page 12 2, page 8 open-ended Q, 14 1, page 15 2, page 15 1st Q, page13 1, page 13  knowledge of OHS noise regulation knowledge of information sources perception of efficacy of ENC in preventing NIHL compared to other prevention measures perception of feasibility  2, page 14  perception of cost as a barrier  3, page 14  perception of other benefits  112  Table: classification of questions into different categories (contd.) Category other  Subcategory  Question number 4, page 6 9, page 6 3, page 12  Audit  Demographics  1, page12 9 of page 6, 1-4 of page16, 5 of page 17 1-11 (except 10) of pages 18-20  description perception about audiometric testing perception about the effectiveness of hearing aids in treating NIHL Knowledge that HPD should be used continuously in noise Reliability check —effectiveness of HPD background information about companies  personal characteristics of respondents  113  Appendix G: Information letter  School of Environmental Health 3rd floor-2206 East Mall Vancouver, B.C. Canada V6T 1Z3 www.soeh.ubc.ca Tel: (604)822-9595 Date Name of the contact person Designation Company Address Re: A study on noise at workplaces and engineered noise control Dear Mr. < name >, Thank you very much for agreeing to participate in the research study on noise at workplace and engineered noise controls. Through this study, we are trying to understand how we can better reduce noise at workplaces. Your company was randomly chosen through BC Manufacturers’ Directory or Yellow Pages. Participation is simple. Please follow the Instructions for distributing the questionnaire attached with this letter.  The participants complete the questionnaire (it takes no more than 20 minutes) and then mail it back to us. A postage paid return envelope is attached to each questionnaire. There is no cost to the participant, and everyone who is asked to participate can have their name entered in a draw for an Apple iPod (value $300). However, providing names or contact information is optional. All the answers are kept confidential. Nobody will be able to identify any of the participants. The information provided will be grouped with other participants. Hearing loss caused from noise exposure at workplaces resulted in several hundred claims accepted by WorkSafeBC in the year 2006 alone. This not only causes significant negative impacts on the lives of the sufferers but also incurs huge financial loss to employers.  114  Research shows that reducing noise (i.e. using engineered noise control) shows the best promise to prevent hearing loss. However, in most workplaces engineered noise controls remain underutilized, while the incidence of noise induced hearing loss remains high indicating the need for a new approach. This study is very important as it will help formulate strategies to create a safe and healthy working environment free of hazardous noise. We hope you will help us in our effort to create a noise-free working environment. If you have any question, please email at mnahid@interchange.ubc.ca, or call (604)822-6777. Sincerely Musarrat Nahid, M.Sc. candidate, School of Environmental Health University of British Columbia  115  

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