Observed arrival · 2026-11-11
BadAirDays maps your county’s bad-air days
A county lookup using EPA monitor records to show how often the AQI topped 100, whether smoke or ozone drove those days, and when they occurred.
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- US residents checking their county’s air-quality patterns
- Worth noticing
- The site says ozone is the main cause in 117 of the 213 counties with at least five bad-air days a year.
Field notes
The lookup counts days when AQI exceeds 100, using EPA monitor records from 2016–2025. It includes 1,089 counties with monitors and intentionally omits counties without them rather than estimating. County pages break the record down by cause and month; the homepage says ozone tends to cluster in June and July, while smoke peaks in August and remains elevated in September.
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