Communities of color are disproportionately exposed to long-term and short-term PM2.5 in metropolitan America

We conducted a novel investigation of neighborhood-level racial/ethnic exposure disparities employing measures aligned with long-term and short-term PM2.5 air pollution benchmarks across metropolitan contexts of the contiguous United States, 2012–2016. We used multivariable generalized estimating equations (GEE) to quantify PM2.5 exposure disparities based on the census tract composition of people of color (POC) and POC groups (Hispanic/Latina/x/o, Black, Asian). We examined eight census tract-level measures of longer-to-shorter term exposures derived from data on modeled daily ambient PM2.5 concentrations. We found associations between increased POC composition and greater exposure to all PM2.5 measures, with associations strengthening across measures of longer-to-shorter term exposures. In a GEE with a negative binomial distribution, a standard deviation increase in POC composition predicted a 0.6% increase (incidence rate ratio (IRR): 1.006, 95% confidence interval (CI): 1.005–1.008) in the number of days PM2.5 concentrations were ≥5 μg/m3 (longest-term benchmark). In a GEE with an inverse Gaussian distribution, a standard deviation increase in POC composition predicted a 0.110 μg/m3 (1.0%) increase (B: 0.110, 95% CI: 0.076–0.143) in mean PM2.5 concentration. In GEEs with a negative binomial distribution, the effect of a standard deviation increase in POC composition on exposure strengthened to 2.6% (IRR:1.026, 95% CI:1.017–1.035), 3.4% (IRR:1.034, 95% CI:1.022–1.047), 4.2% (IRR:1.042, 95% CI:1.025–1.058), 16.2% (IRR:1.162, 95% CI:1.117–1.210), 22.7% (IRR:1.227, 95% CI:1.137–1.325) and 28.3% (IRR:1.283, 95% CI:1.144–1.439) with respect to the number of days PM2.5 concentrations were ≥10, 12, 15, 25, 35 and 55.5 μg/m3. POC group models indicated exposure disparities based on greater Hispanic/Latina/x/o, Asian, and Black composition. Evidence for stronger POC associations with shorter-term (higher concentration) PM2.5 exceedances suggests that reducing PM2.5 would attenuate racial/ethnic exposure disparities. •Novel national environmental justice study of long- and short-term PM2.5 pollution.•People of color (POC) live with significantly worse longer- and shorter-term PM2.5.•Disparities are greatest based on Hispanic/Latina/x/o, Asian, and Black status.•Relative disparities for POC worsen across longer-to-shorter-term PM2.5 measures.•POC disparities in PM2.5 exposures have important research and policy implications.