Smoke: keep one room clean
Shut the windows and run an air purifier sized for the room.
Wildfire smoke guide →Air quality in Arizona, county by county
13 Arizona counties have enough EPA monitor data to count bad-air days. Weighted by population, they averaged about 67 days a year from 2021 to 2025 when the air was unhealthy for sensitive groups or worse.
CDC's model, which estimates every county from monitors and satellites, gives the average Arizona county, weighted by population, about 1 smoky day (fine particles over 35.4 µg/m³, mostly wildfire smoke) and about 25 high-ozone days a year at its worst spot (2018 to 2022). See every county on the map.
Every Arizona county with monitors
Most bad-air days first. 12 have a full report. Compare with the worst and the cleanest counties in the US.
| County | Bad-air days a year | |
|---|---|---|
| Maricopa CountyPhoenixOzone | 100.0 | |
| Pinal CountyMaricopaDust | 47.6 | |
| Gila CountyPaysonOzone | 16.8 | |
| Pima CountyTucsonOzone and particles | 10.8 | |
| Yuma CountyYumaDust | 7.4 | |
| Cochise CountySierra VistaOzone | 4.6 | |
| Santa Cruz CountyNogalesWinter particlesozone not measured | 3.2 | |
| Coconino CountyFlagstaffOzone | 2.4 | |
| La Paz CountyOzone | 2.0 | |
| Mohave CountyLake Havasu CityDustozone not measured | 0.8 | |
| Yavapai CountyPrescott ValleyRarely bad | 0.4 | |
| Apache CountyRarely bad | 0.2 | |
| Navajo CountyShow LowRarely bad | 0.2 | |
| No Arizona county with a monitor matches “”. Counties without a monitor aren't listed; a neighbor's numbers are a fair guide, or find it on the map. | ||
Counties without a monitor aren't listed. Air doesn't stop at the county line, so a neighbor's numbers are a fair guide.
What helps on a bad-air day
Check AirNow for today's reading and tomorrow's forecast, then match the step to the pollutant.
Upgrade the furnace filter
MERV 13 catches far more smoke than thin fiberglass filters.
Furnace filters →Questions people ask about air quality in Arizona
Which county in Arizona has the worst air?
Among Arizona counties with EPA monitors, Maricopa County had the most bad-air days from 2021 to 2025: about 100 bad-air days a year with an AQI over 100. That's about 1 day in 4.
How often is the air bad in Arizona?
Weighted by population, Arizona counties with monitors averaged about 67 bad-air days a year from 2021 to 2025 with an AQI over 100, when children, older adults and people with asthma should cut back outdoors. That's about 1 day in 5.
Which county in Arizona has the cleanest air?
Of the 13 counties with enough monitor data, 2 counties tied for the fewest (Apache County and Navajo County): 0.2 a year from 2021 to 2025. Counties without monitors aren't ranked.
Where can I check today's air quality in Arizona?
AirNow, run by the EPA and its partners, shows current readings and forecasts by ZIP code, and its fire and smoke map adds smoke plumes and low-cost sensors.
Sources: EPA AirData county AQI summaries, 2021 to 2025; CDC Environmental Public Health Tracking Network modeled PM2.5 and ozone, 2018 to 2022. Updated November 8, 2026.