Washington Department of Ecology, GIS Technical Services (2023). Air Quality Non-Attainment Areas: Particulate Matter Less Than 2.5 Microns (PM2.5) [Washington (State)]. . https://geo.wa.gov/datasets/waecy::air-quality-non-attainment-areas-particulate-matter-less-than-2-5-microns-pm2-5-1 (dataset)