New Haven Air Quality in 2021
In 2021, New Haven's air quality (New Haven-Milford, CT area) had a median daily AQI of 46 (Good) across 365 monitored days. 14 days (3.8%) reached Unhealthy for Sensitive Groups or worse, 220 were Good, and the year's peak AQI was 159 (Unhealthy). Fine particulate matter (PM2.5) set the daily AQI on 218 of those days. The cleanest month of 2021 was October (median AQI 39, 0 days above 100) and the worst was August (median 48, 6 days above 100, peak 150).
- Good: 60.3%
- Moderate: 35.9%
- Unhealthy for Sensitive Groups: 3.3%
- Unhealthy or worse: 0.5%
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How was New Haven's air quality in 2021?
Good on a typical day: median AQI 46, with 14 days above AQI 100 out of 365 monitored — the 7th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2021: 159 (Unhealthy).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 218 days.
- ✓Cleanest month: October; worst: August.
Frequently asked questions
What was the average AQI in New Haven in 2021?▾
EPA's Air Quality System puts New Haven's (New Haven-Milford, CT) median daily AQI for 2021 at 46, which is Good. 14 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 2021?▾
The cleanest month of 2021 was October (median AQI 39, 0 days above 100) and the worst was August (median 48, 6 days above 100, peak 150).
Was 2021 a good or bad year for New Haven's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 7th cleanest by days above AQI 100 — the worst year on record here. 2021's median of 46 is in line with the area's typical annual median of 44.
New Haven month by month in 2021
New Haven air quality month by month, 2021 (New Haven-Milford, CT, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 42 | 0 | 95 | PM2.5 |
| February | 28 | 48 | 0 | 72 | PM2.5 |
| March | 31 | 44 | 0 | 76 | PM2.5 |
| April | 30 | 41 | 0 | 77 | O3 |
| May | 31 | 40 | 0 | 97 | O3 |
| June | 30 | 52 | 4 | 143 | O3 |
| July | 31 | 54 | 4 | 159 | PM2.5 |
| Augustworst | 31 | 48 | 6 | 150 | O3 |
| September | 30 | 42 | 0 | 58 | PM2.5 |
| Octobercleanest | 31 | 39 | 0 | 54 | PM2.5 |
| November | 30 | 43 | 0 | 70 | PM2.5 |
| December | 31 | 55 | 0 | 75 | PM2.5 |
How 2021 compares
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 7th cleanest by days above AQI 100 — the worst year on record here.
2021's median of 46 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 48 (PM2.5). 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.