WADOHThis feature layer represents 5 kilometer (km) grid cell estimates of fine particulate matter (PM 2.5 ) annual design values from 2022-2024 in micrograms per cubic meter (µg/m3). Spikes in PM2.5 due to wildfire smoke are not included in these calculations, since wildfire smoke exposure is scored separately. Daily average PM 2.5 concentrations are estimated by combining the National Oceanic and Atmospheric Administration (NOAA) forecast model with measured concentrations from the Washington Ambient Air Monitoring Network. The NOAA forecast model accounts for emissions, meteorology, and topography. These daily averages are used to calculate annual design values, which are 3-year averages of annual mean concentrations (as defined by EPA for comparison to the federal annual PM 2.5 standard). Long-term exposure to these tiny particles can harm heart and lung health and contribute to chronic diseases. People most affected include children, older adults, individuals with asthma or other breathing problems, outdoor workers, and communities with fewer financial resources who may have fewer ways to reduce exposure. This data was created by the Washington Department of Ecology and sent to the EHD map team. Citation Washington Tracking Network, Washington State Department of Health. Web. "PM2.5 Annual Concentration". Data obtained from the Department of Ecology, 2022-2024 Data. Published September 2025. Contact us at EHDMap@doh.wa.gov if you have questions or comments.ArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/e52f26831706482891792ae185fdef0d_0engState of Washington Geospatial Open Data PortalPublicPM2.5 Annual Concentration [Washington (State)]Web servicesWashington (State)Last Modified: 2026-01-15