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Air quality in New Jersey

EPA monitors report from 16 of New Jersey’s 21 counties. That is the honest limit of this page: the other 5 are not measured, not clean. In 2025 the most affected monitored county was Mercer County, with 6 days above the moderate category.

16
Counties with monitors
5
Counties without
42
Days above moderate, 2025
Summed across monitored counties
8.9%
Adults with asthma
Population-weighted county estimate

County by county

Monitored New Jersey counties

GoodModerateUnhealthy for sensitive groupsUnhealthyVery unhealthyHazardous
County90th %ile AQIAbove moderateMax AQI2025 days by category
Mercer County636126
Monmouth County506161
Bergen County614136
Passaic County614115
Cumberland County593123
Gloucester County583143
Hudson County593133
Hunterdon County613122
Morris County593129
Camden County642168
Atlantic County541105
Middlesex County571112
Ocean County581154
Union County611111
Warren County611105
Essex County61097

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

5 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