{"datasets":[{"cadence":"P6M","check_every":"P1D","coverage":{"end":"2026","start":"1980"},"current":"2026-10-26.271cefd8c0","description":"EPA's yearly Air Quality Index (AQI) summary for every US county with a monitor, from 1980: how many days fell in each AQI category, the maximum, 90th-percentile and median daily AQI, and how many days each pollutant set the AQI. Validated EPA AirData; the latest year is partial until EPA's next release completes it.","discontinued":false,"id":"county-aqi-annual","kind":"series","published_at":"2026-10-26T12:14:20Z","sla":"P8M","source":{"commercial_ok":true,"license":"LicenseRef-US-Government-Work","name":"EPA AirData annual AQI by county","url":"https://aqs.epa.gov/aqsweb/airdata/download_files.html"},"title":"Yearly air quality summary by county"},{"cadence":"P1D","check_every":"P1D","coverage":{"end":"2026-10-25","start":"1980-01-01"},"current":"2026-10-26.2a0d912802","description":"The daily Air Quality Index (AQI) for every US county with an EPA monitor, from 1980 to yesterday. Rows up to EPA's latest AirData release are validated (validated: true). Later days are preliminary (validated: false): EPA AirNow data from federal, state, local and tribal agencies, not yet verified and subject to change. For those days the county AQI is a derived value calculated by airdata.dev as the highest site AQI reported to AirNow in the county that day, the way EPA summarizes a county; the site AQI values themselves are as received. Preliminary days cover ozone, PM2.5, PM10 and CO only. A preliminary row never replaces a validated one.","discontinued":false,"id":"county-aqi-daily","kind":"series","published_at":"2026-10-26T12:16:27Z","sla":"P4D","source":{"commercial_ok":true,"license":"LicenseRef-US-Government-Work AND LicenseRef-AirNow-Data-Exchange-Guidelines","name":"EPA AirData daily AQI by county (validated) and EPA AirNow daily data files (preliminary)","url":"https://aqs.epa.gov/aqsweb/airdata/download_files.html"},"title":"Daily air quality index by county"}],"site":"airdata"}