New Haven Air Quality in 2025
In 2025, New Haven's air quality (New Haven-Milford, CT area) had a median daily AQI of 43 (Good) across 365 monitored days. 13 days (3.6%) reached Unhealthy for Sensitive Groups or worse, 245 were Good, and the year's peak AQI was 159 (Unhealthy). Ground-level ozone set the daily AQI on 226 of those days. The cleanest month of 2025 was October (median AQI 31, 0 days above 100) and the worst was June (median 63, 5 days above 100, peak 151).
- Good: 67.1%
- Moderate: 29.3%
- Unhealthy for Sensitive Groups: 3.0%
- Unhealthy or worse: 0.5%
Reduce Indoor Ozone in New Haven
Today's main pollutant in New Haven is ground-level ozone (AQI 32). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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How was New Haven's air quality in 2025?
Good on a typical day: median AQI 43, with 13 days above AQI 100 out of 365 monitored — the 4th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2025: 159 (Unhealthy).
- ✓Ground-level ozone was the main pollutant on 226 days.
- ✓Cleanest month: October; worst: June.
Frequently asked questions
What was the average AQI in New Haven in 2025?▾
EPA's Air Quality System puts New Haven's (New Haven-Milford, CT) median daily AQI for 2025 at 43, which is Good. 13 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 159.
Which month had the worst air quality in New Haven in 2025?▾
The cleanest month of 2025 was October (median AQI 31, 0 days above 100) and the worst was June (median 63, 5 days above 100, peak 151).
Was 2025 a good or bad year for New Haven's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2025 ranks 4th cleanest by days above AQI 100. 2025's median of 43 is in line with the area's typical annual median of 44.
New Haven month by month in 2025
New Haven air quality month by month, 2025 (New Haven-Milford, CT, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 37 | 0 | 69 | O3 |
| February | 28 | 37 | 0 | 71 | O3 |
| March | 31 | 42 | 0 | 56 | O3 |
| April | 30 | 44 | 0 | 77 | O3 |
| May | 31 | 41 | 0 | 67 | O3 |
| Juneworst | 30 | 63 | 5 | 151 | O3 |
| July | 31 | 58 | 5 | 159 | O3 |
| August | 31 | 53 | 3 | 129 | O3 |
| September | 30 | 40 | 0 | 97 | O3 |
| Octobercleanest | 31 | 31 | 0 | 80 | O3 |
| November | 30 | 36 | 0 | 75 | PM2.5 |
| December | 31 | 34 | 0 | 66 | PM2.5 |
How 2025 compares
Among the 7 years EPA has published for the area (2019–2025), 2025 ranks 4th cleanest by days above AQI 100.
2025's median of 43 is in line with the area's typical annual median of 44.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in New Haven
The latest EPA AirNow observation puts New Haven's AQI at 32 (O3). The figures above are multi-year annual statistics, not today's reading.
View current New Haven air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (New Haven-Milford, CT), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.