Air quality tools
Air Quality Tools
Four free, interactive tools built on EPA Air Quality System data, look up, compare, rank, and translate the air quality of any U.S. county.
- 995
- Counties covered
- 4
- Interactive tools
- 75.4%
- US avg good days
AQI Lookup
Search any U.S. county for its median AQI, EPA category, and good-day share.
County Compare
Put two or three counties side by side on the metrics that matter.
Cleanest Counties Finder
Rank the cleanest or most-polluted counties by state.
AQI Health Calculator
Enter an AQI value to see its category and EPA health guidance.
Cleanest county right now
Kenai Peninsula County, Alaska
100.0% good-air days, median AQI 8.
Most polluted county right now
Maricopa County, Arizona
9.0% good-air days, median AQI 77.
Frequently asked questions
What can the PlainAir tools do?
The tools let you look up any county’s air quality, compare counties side by side, rank the cleanest or most-polluted counties by state, and translate any AQI value into plain-language health guidance. Each one runs on the same EPA Air Quality System data behind the rest of the site.
Is the data the same as the county pages?
Yes. Every tool queries the same EPA Air Quality System figures shown on the county, metro, and state profiles, so a value you find in a tool matches the full profile it links to. Nothing is estimated or fabricated.