Air Quality Rankings for Delaware 2026
Delaware has 3 cities with EPA air quality data. Kent, Delaware has the cleanest air with a 5-year average AQI of 43. New Castle, Delaware has the highest AQI at 48.
| # | City | 5yr Avg AQI | Current AQI | Worst Pollutant | Trend | Grade |
|---|---|---|---|---|---|---|
| 1 | Kent, Delaware | 43 | 46 | Ozone | Stable | B |
| 2 | Sussex, Delaware | 43 | 47 | Ozone | Improving | B |
| 3 | New Castle, Delaware | 48 | 51 | PM2.5 | Improving | C |
Air quality data for Delaware is sourced from the EPA Air Quality System (AQS), which monitors outdoor air quality at thousands of stations nationwide.
Frequently Asked Questions
Kent, Delaware has the best air quality in Delaware with a 5-year average AQI of 43 and a grade of B.
Delaware has 3 cities with EPA air quality monitoring data in our database, covering multiple years of AQI measurements.
The Air Quality Index (AQI) measures five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Lower AQI values indicate cleaner air — 0-50 is "Good," while 150+ is "Unhealthy."
Cities ranked by 5-year average AQI (lower is better). Grades factor in average AQI, trend direction, unhealthy days, and dominant pollutant.