Hartford Air Quality in 2021
In 2021, Hartford's air quality (Hartford-West Hartford-East Hartford, CT area) had a median daily AQI of 43 (Good) across 365 monitored days. 15 days (4.1%) reached Unhealthy for Sensitive Groups or worse, 243 were Good, and the year's peak AQI was 151 (Unhealthy). Fine particulate matter (PM2.5) set the daily AQI on 189 of those days. The cleanest month of 2021 was October (median AQI 36, 0 days above 100) and the worst was June (median 49, 7 days above 100, peak 151).
- Good: 66.6%
- Moderate: 29.3%
- Unhealthy for Sensitive Groups: 3.8%
- Unhealthy or worse: 0.3%
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How was Hartford's air quality in 2021?
Good on a typical day: median AQI 43, with 15 days above AQI 100 out of 365 monitored — the 7th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2021: 151 (Unhealthy).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 189 days.
- ✓Cleanest month: October; worst: June.
Frequently asked questions
What was the average AQI in Hartford in 2021?▾
EPA's Air Quality System puts Hartford's (Hartford-West Hartford-East Hartford, CT) median daily AQI for 2021 at 43, which is Good. 15 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 151.
Which month had the worst air quality in Hartford in 2021?▾
The cleanest month of 2021 was October (median AQI 36, 0 days above 100) and the worst was June (median 49, 7 days above 100, peak 151).
Was 2021 a good or bad year for Hartford'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 43 is in line with the area's typical annual median of 43.
Hartford month by month in 2021
Hartford air quality month by month, 2021 (Hartford-West Hartford-East Hartford, CT, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 39 | 0 | 93 | PM2.5 |
| February | 28 | 45 | 0 | 72 | PM2.5 |
| March | 31 | 43 | 0 | 74 | O3 |
| April | 30 | 44 | 0 | 84 | O3 |
| May | 31 | 40 | 1 | 101 | O3 |
| Juneworst | 30 | 49 | 7 | 151 | O3 |
| July | 31 | 52 | 4 | 136 | PM2.5 |
| August | 31 | 49 | 3 | 129 | O3 |
| September | 30 | 40 | 0 | 74 | PM2.5 |
| Octobercleanest | 31 | 36 | 0 | 52 | PM2.5 |
| November | 30 | 41 | 0 | 73 | PM2.5 |
| December | 31 | 53 | 0 | 68 | 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 43 is in line with the area's typical annual median of 43.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Hartford
The latest EPA AirNow observation puts Hartford's AQI at 19 (PM2.5). The figures above are multi-year annual statistics, not today's reading.
View current Hartford air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Hartford-West Hartford-East Hartford, 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.