Fig. 1: Maps of the spatial distributions of air pollutants studied.

The three panels present the average concentrations of a annual PM2.5 (μg/m³)16, b annual NO2 (ppb)17, and c warm-season O3 (ppb)18 at 1-km2 resolution across the contiguous United States over the study period, respectively. Map was made from the census bureau shapefile (cb_2017_us_county_500k.shp, https://www2.census.gov/geo/tiger/GENZ2017/shp/) using R software, and no licenses are required as this map was provided free of any copyright restrictions. Source data are provided as a Source Data file.