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The EPA air-quality releases this site is built on, cleaned and joined, as plain CSV or JSON. No sign-up, no rate limit, no attribution beyond a link.
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Annual AQI by county (2025)
One row per county: days with a valid AQI reading, the split across the six EPA categories, and median, 90th-percentile and maximum AQI.
1,002 counties · mirrors EPA annual_aqi_by_county_2025
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Annual AQI by metro area (2025)
One row per EPA Core Based Statistical Area: monitored-day category counts plus median, 90th-percentile and maximum AQI. CBSA scope is explicit; these are not city-limit measurements.
504 CBSAs · mirrors EPA annual_aqi_by_cbsa_2025
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Annual AQI by state (2025)
A transparent county rollup with the typical-county rate and the monitored-day share kept as separate, labelled measures.
53 states and territories · mirrors EPA annual_aqi_by_county_2025
The underlying EPA measurements are public domain. These compilations, meaning the cleaning, the joins and any derived columns (labelled as ours on each dataset page), are released under CC BY 4.0.
Revenue readiness (not activated)
This page is the productized citability surface: live CSV and JSON downloads for every dataset listed above, plus an embed card, under CC BY 4.0 with attribution by link. No pricing page, API key, or paid tier exists. Activation of any paid data product is an operator decision.
Affiliate units are not live. If they ever are, they stay off interpretive health or exposure advice and off the primary data verdict, use clear labeling, and share Module 36 density ceilings with display ads. None of that is enabled here.
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Every figure on PlainAirData is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. Each dataset page reads its figures from the same query its CSV and JSON endpoints serve, so a page and its downloads cannot state different totals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2025 EPA annual summary; source refresh checked August 2026.