Skip to content
lung.com

Air quality in Arizona

EPA monitors report from 13 of Arizona’s 15 counties. That is the honest limit of this page: the other 2 are not measured, not clean. In 2025 the most affected monitored county was Maricopa County, with 38 days above the moderate category.

13
Counties with monitors
2
Counties without
114
Days above moderate, 2025
Summed across monitored counties
10.4%
Adults with asthma
Population-weighted county estimate

County by county

Monitored Arizona counties

GoodModerateUnhealthy for sensitive groupsUnhealthyVery unhealthyHazardous
County90th %ile AQIAbove moderateMax AQI2025 days by category
Maricopa County10138366
Pinal County100341,215
Gila County8715196
Pima County808357
Yuma County697211
Cochise County714328
Santa Cruz County733187
Coconino County712113
Mohave County342331
La Paz County641253
Apache County580100
Navajo County24054
Yavapai County67097

EPA Air Quality System annual summaries by county, 2025. The 90th percentile AQI describes a day worse than nine out of ten, which is a steadier measure than the annual maximum a single wildfire can set.

Not measured

2 counties without a monitor

No EPA monitor reported from these counties, so there is no air quality record to publish. Their radon zone is known, and radon is measured in the building rather than the air outside it.

Other states

Air quality elsewhere