Mortality associated with long-term PM2.5 exposure among overburdened communities in Washington State

Long-term exposure to fine particulate matter (PM_2.5) increases all-cause mortality risk. Few studies have examined PM_2.5-associated mortality in Washington State communities experiencing health, social, and environmental inequities and highly impacted by criteria air pollution (overburdened communities). We used the U.S. Environmental Protection Agency’s Benefits Mapping and Analysis Program, Community Edition, to estimate PM_2.5-associated mortality in 16 overburdened communities in Washington. The model included baseline and natural background PM_2.5 concentrations, census tract population data, baseline mortality rates from state death records, and published PM_2.5 and all-cause mortality effect estimates. We calculated age-adjusted mortality rates by standardizing crude rates to the statewide age distribution. The annual mean PM_2.5 concentration in overburdened communities was 7.2 µg/m³ during 2014–2017 compared to the state average, 6.4 µg/m³. We estimated 46 annual PM_2.5-associated deaths (95% confidence interval: 33–59) per 100,000 people in overburdened communities after age adjustment compared with 25 (12–37) deaths per 100,000 people statewide. Age-adjusted annual PM_2.5-associated mortality rates were highest among Hispanic and non-Hispanic Black people (78 [44–110] and 56 [17–92] deaths per 100,000 people, respectively). Similar disparities were observed when using 2020 air quality data that included more extensive wildfire-related PM_2.5. Despite meeting the National Ambient Air Quality Standards, we identified racial and ethnic disparities in PM_2.5-associated mortality in Washington overburdened communities. In addition to enhanced air quality monitoring, engagement with local governments, Tribal nations, air agencies, and community-based organizations will be crucial for understanding and addressing disproportionate PM_2.5 impacts in these communities.