1165505 - Wildfires and the Changing Landscape of Air Pollution-Related Health Burden

Wildfires are a growing source of fine particulate (PM2.5) pollution; however, the health burden associated with this increase is not well characterized. We investigated trends and disparities in PM2.5-related health burden for all days and wildfire smoke-impacted days across California between 2008 and 2016. Health burden was evaluated for asthma, chronic obstructive pulmonary disease, all-cause respiratory and cardiovascular emergency department (ED) visits and hospital admissions. Using previously developed daily PM2.5 predictions to estimate exposure across residential ZIP codes, we generated California-specific, population level, and demographic subgroup (age, gender, race/ethnicity) specific associations between daily PM2.5 and outcomes. Health burden was evaluated using relative risk estimates and attributable counts and fractions by demographic and geographic factors and over time.

PM2.5-attributed burden steadily decreased over the study period, whereas the fraction attributed to wildfire smoke varied by fire season intensity, comprising up to 15% of the total PM2.5 burden. The highest PM2.5-attributed annual burden rate was observed for respiratory ED visits with 92 per 100,000 persons. Per 1 µg/m3 change in PM2.5, the relative risk was highest for respiratory and asthma outcomes, accounting for a larger fraction of the outcome-specific annual burden. Disparities in total- and wildfire-PM2.5 attributed burden were observed by age and race/ethnicity, reflecting differences in underlying morbidity, exposure, and risk measures. Rural, central, and northern California populations experienced increased wildfire-attributed burden rates.

Wildfires have significantly impacted the PM2.5-related health burden in California, and such impacts disproportionately affect demographic groups and regions already vulnerable to poor air quality.