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Lan, Qingyi

University of British Columbia

The British Columbia (BC) wildfire seasons of 2017 and 2018 were unprecedented in terms of the area they burned and the smoke they emitted. Wildfire smoke is a complex and dynamic mixture of air pollutants, of which fine particulate matter (PM2.5) is generally recognized as the greatest threat to human health. Very few studies have examined how exposure to PM2.5 influences in utero respiratory tract development processes, so the most concerning prenatal exposure windows remain unknown. In this thesis, all infants in utero during the wildfire seasons (July to September) of 2016-2019 were identified using the BC Perinatal Data Registry (BCPDR). Residential addresses of the mothers and their infants were used to estimate daily PM2.5 exposures throughout pregnancy and the first year of life using the Canadian Optimized Statistical Smoke Exposure Model (CanOSSEM) at a resolution of 5x5 km². Outcomes of interest and potential covariates for each infant in the first year of life were identified through data linkage and compared during critical windows of prenatal respiratory tract development using the Cox proportional hazard model. We found that the sensitive windows for respiratory infections and associated amoxicillin dispensations move to the later stages of development as the respiratory infections of interest move from the upper respiratory tract to the lower respiratory tract. Each 1 mg/m3 increase in PM2.5 exposure was associated with earlier diagnosis of otitis media in the first window (week 0-9) of the Eustachian tube development (HR=1.012, 95%CI: 1.004-1.021). Each 1 mg/m3 increase in PM2.5 exposure was associated with earlier diagnosis of lower respiratory infections in the Saccular stage (week 28-36) (HR =1.015, 95%CI: 1.010-1.020) and Alveolar stage (week 36 to birth) (HR = 1.008, 95%CI: 1.004-1.012). Similar results were observed for the effect of wildfire-related PM2.5 on amoxicillin dispensations related to respiratory tract infections in the first year of life. The statistically significant associations between wildfire-related PM2.5 and overall amoxicillin dispensation were detected for the later stages of respiratory tract development. Our results suggest that it is necessary to formulate clear public health guidelines for pregnant mothers to avoid being exposed to wildfire during wildfire seasons.

Text

2022-09-14

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/82713

Population and Public Health

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/