# Counties in New Hampshire by median Air Quality Index (US EPA), 2003

All 9 values come from U.S. Environmental Protection Agency for 2003, so the places are comparable. 1 counties have no value for that period and are not ranked.

- Indicator id: `aqi_median`
- Unit: index
- Definition: Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries. The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide). Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.
- Source: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: median daily AQI (https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual)
- Publisher page: https://invokely.ai/en/publishers/environmental-protection-agency
- Retrieved: 2026-10-12
- Citation: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
- Web page: https://invokely.ai/rankings/median-air-quality-index/new-hampshire-counties

| Rank | Place | index |
|---:|---|---:|
| 1 | Coos County | 48 |
| 2 | Sullivan County | 42 |
| 3 | Cheshire County | 41 |
| 3 | Hillsborough County | 41 |
| 5 | Belknap County | 40 |
| 6 | Merrimack County | 39 |
| 7 | Rockingham County | 38 |
| 7 | Strafford County | 38 |
| 9 | Grafton County | 35 |