Wildfires and the Changing Landscape of Air Pollution–related Health Burden in California
We characterized trends in fine particulate matter (PM2.5) related health burden across California residential ZIP codes (2008-2016), focusing on asthma, chronic obstructive pulmonary disease, and all-cause respiratory and cardiovascular emergency department (ED) visits and hospital admissions (HAs). We estimated health burden rates and characterized the fraction of the overall morbidity attributed to PM2.5, total and on days with wildfire smoke, by year, demographic factors, and geography. We used previously developed exposure datasets for PM2.5 and satellite-derived products to identify wildfire smoke-impacted days.
We estimated an excess of 300,000 respiratory and 129,000 cardiovascular ED visits attributed to total PM2.5. PM2.5-attributed burden decreased over the period, whereas the fraction attributed to wildfire smoke varied by intensity of the fire season; up to 17% of the total PM2.5-burden; the amount approximately equal to the amount that would be reduced over two years in total PM2.5. Disparities in wildfire-PM2.5-burden were observed by race and ethnicity, among the oldest age group, publicly insured and within rural communities reflecting both the observed differences in underlying morbidities and exposures. Central and northern California had the greatest wildfire related burden both due to susceptibility and increased exposure.
Wildfire activity in California threatens to offset the health benefits gained by improvements in air quality. These impacts disproportionately affect demographic groups already recognized for vulnerabilities and regions with known vulnerabilities.