Indicator · us-max-aqi
Worst air day (highest AQI)
The single worst day; one wildfire or fireworks night can set it.
- Unit
- AQI
- Places
- 916 counties in 2025
- Built from
- Yearly air quality summary by county
- Reading it
- Lower is better.
Map and compare every county on visualizedata.org →
Median county, 1980–2025
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Show the data as a table
Highest and lowest in 2025
| El Paso County, TX | 2,122 AQI |
|---|---|
| Pinal County, AZ | 1,215 AQI |
| St. Louis city, MO | 738 AQI |
| Platte County, WY | 723 AQI |
| Mono County, CA | 704 AQI |
| Karnes County, TX | 32 AQI |
|---|---|
| Sonoma County, CA | 39 AQI |
| Wilson County, TX | 41 AQI |
| Carbon County, WY | 43 AQI |
| Uinta County, WY | 50 AQI |
How it is computed
EPA max AQI, from the Yearly air quality summary by county dataset on this site. visualizedata.org computes the indicator for every place and year; the full table, the map and each place's history are on its page there. The underlying data, with its source and license, is on the dataset page, with the API and downloads.