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UBC Theses and Dissertations

Air quality and visibility in southwestern British Columbia during forest fire smoke events Keane, Jenna Christine


In recent years, the frequency of forest fires has been increasing in western North America. With an increase in forest fire activity, attention has been drawn to the negative effects forest fire smoke has on air quality and visibility. This study quantifies the relationship between smoke, air quality and visibility. Determining how much smoke produced by forest fires influences air quality and visibility will improve air quality forecasting. This study was conducted from 2007 through 2011 during the fire season (April - October) in southwestern British Columbia, focusing on the Georgia Basin airshed. A host of tools were used to determine how air quality and visibility were influenced by forest fire smoke. Satellite Fire Detection from National Oceanic and Atmospheric Administration (NOAA)’s, National Geophysical Data Centre(NDGC) was used to determine on which days during the four year period smoke was present in southwestern British Columbia. To determine where smoke particles were transported from, NOAA’s HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model was used. Backward trajectories were computed from Vancouver International Airport on days which smoke was present. PM₂.₅ (particles with a diameter less than 2.5 microns) and O₃ (ozone) concentrations were examined at twelve locations. Gases and aerosols produced by forest fires are known to degrade visibility. A semi-automated approach was used to calculate visibility using digital images. Southwestern British Columbia's air quality and visibility was negatively influenced by smoke. Up to 30% of summer days in the Georgia Basin airshed were influenced by smoke. The summer of 2009 experienced the most smoke days. Smoke and aerosol concentrations were largely influenced by dominating weather patterns. Two weather patterns dominate in the Georgia Basin airshed on smoke days. One pattern creates favourable conditions to produce forest fires and the other is likely to transport smoke from the interior of British Columbia into the Georgia Basin airshed. Concentrations of fine particulate matter increased on average by 5 µgm⁻³ and ozone increased by 7 ppb when smoke was present. Visual range (VR) decreased on average by 60 km and estimated extinction values increased during smoke events.

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