When smoke comes to town: a long-term health impact assessment of acute and chronic wildfire smoke exposure

Abstract:

Smoke from wildland fires has a significant impact on air quality in the United States (US) accounting for over 30% of US primary fine particulate matter (PM_2.5) emissions. As large fires continue to increase in frequency/area and anthropogenic emissions decline, wildfires are projected to become the dominant source of PM_2.5 in the US by the end of the century. The health impacts of fire-sourced PM_2.5 may differ from anthropogenic sources due to differences in composition and particle size distribution, as well as differences in co-emitted pollutants. However, most health impact assessments of wildfire smoke exposure rely on risk ratios developed from studies that use exposure to anthropogenic-sourced PM_2.5. Several recent epidemiology studies have estimated risk ratios for many acute outcomes of wildfire smoke exposure, which have not yet been applied in health impact assessments of smoke exposure.

In this work, we use wildfire smoke-specific risk ratios along with observation-based smoke PM_2.5 estimates to conduct a health impact assessment of US wildfire smoke from 2006-2018. We provide estimates of several identified acute outcomes of smoke exposure including asthma hospitalizations, doctor’s office visits, inhaler medication fills, and mortality over this time period. We also provide updated estimates of US mortality and disability adjusted life years (DALYs) due to chronic smoke exposure using observation-based smoke PM_2.5 concentrations. We compare the DALYs for chronic exposure to smoke PM_2.5 to DALYs for exposure to several dominant gas-phase hazardous air pollutants in smoke including formaldehyde, acrolein, benzene, and hydrogen cyanide. This analysis allows us to investigate the potential chronic health impact of these co-emitted pollutants, currently not directly included in health impact assessments of wildfire smoke.