Surface Films as a Mediator of Long-Term Air Quality and Health Impacts of Wildfire Smoke Events

SARAH STYLER, Iris Chan, Stephanie Schneider, Annie Cheng, McMaster University

     Abstract Number: 555
     Working Group: Biomass Combustion: Outdoor/Indoor Transport and Indoor Air Quality

Abstract
Wildfire smoke is a major contributor to summertime air quality reductions in urban areas across the western United States and in Canada’s western provinces. Urban environments present many surfaces (e.g., buildings, roadways) to which pollutants can partition. Importantly, although the composition of urban surface films in a given area generally reflects that of co-located particulate matter (PM) samples, it also has a ‘memory effect’, in that transient alterations in PM composition result in long-term changes in film composition. In this context, we hypothesized that the composition of urban surface films in wildfire-influenced regions will reflect smoke influence, long after the smoke itself has dissipated, with attendant consequences for urban air quality and health. To explore this possibility, we deployed a network of low-cost surface film samplers in Summer 2022 in three types of environments: background, smoke-influenced, and smoke-dominated. Through intercomparison of site-specific film compositions, comparison of film data with compositional data from co-located PM stations (where available), and back-trajectory analysis, we provide comprehensive insight into wildfire smoke contamination of urban surfaces.