Air quality in Delaware
EPA monitors report from 3 of Delaware’s 3 counties. That is the honest limit of this page: the other 0 are not measured, not clean. In 2025 the most affected monitored county was Kent County, with 4 days above the moderate category.
3
Counties with monitors
0
Counties without
9
Days above moderate, 2025
Summed across monitored counties
10.8%
Adults with asthma
Population-weighted county estimate
County by county
Monitored Delaware counties
GoodModerateUnhealthy for sensitive groupsUnhealthyVery unhealthyHazardous
| County | 90th %ile AQI | Above moderate | Max AQI | 2025 days by category |
|---|---|---|---|---|
| Kent County | 62 | 4 | 122 | |
| New Castle County | 67 | 4 | 161 | |
| Sussex County | 57 | 1 | 105 |
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.
Other states
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