Air Quality in New Hampshire
New Hampshire has 7 counties with EPA air quality monitoring. Air quality is stable across the state, with an average of 297 "Good" days per county per year. The best air quality is in Belknap (median AQI 35) and the most polluted is Coos (median AQI 44).
| County | Median AQI | Max AQI | Good Days | Unhealthy Days | Trend | Top Pollutant |
|---|---|---|---|---|---|---|
| Belknap | 35 | 78 | 311 | 0 | → stable | PM2.5 |
| Cheshire | 36 | 93 | 302 | 0 | → stable | Ozone |
| Coos | 44 | 90 | 296 | 0 | → stable | Ozone |
| Grafton | 35 | 80 | 334 | 0 | → stable | Ozone |
| Hillsborough | 37 | 97 | 328 | 0 | → stable | Ozone |
| Merrimack | 37 | 74 | 205 | 0 | → stable | Ozone |
| Rockingham | 38 | 122 | 306 | 1 | → stable | Ozone |