New Haven Air Quality in March
Across 2019–2025, New Haven's March air quality had a median AQI of 43 (Good) over 217 monitored days in the New Haven-Milford, CT area. 0.0% of March days (0 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 60.8% of days. The cleanest March on record here was 2020 (median AQI 42, 0 days above 100) and the worst was 2019 (median 49, 0 days above 100, peak AQI 86).
- Good: 74.2%
- Moderate: 25.8%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
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 is the air in New Haven in March?
Good on a typical day: median AQI 43 across 2019–2025, with 0.0% of March days above AQI 100. Ground-level ozone is the main driver.
- ✓74.2% of March days were Good (AQI 0–50), 25.8% Moderate (51–100).
- ✓0 days of 217 reached AQI 101+; the March peak was 86.
- ✓Best March: 2020; worst March: 2019.
Frequently asked questions
What is the air quality like in New Haven in March?▾
Across 2019–2025, the median daily AQI in New Haven in March was 43 (Good). 74.2% of days were Good, 25.8% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is March a good time for outdoor exercise in New Haven?▾
A typical March day in New Haven sits in the Good range (median AQI 43), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of March days reached AQI 101+ in 2019–2025.
Which pollutant causes New Haven's March air quality problems?▾
Ground-level ozone set the daily AQI on 60.8% of March days in New Haven. The highest March AQI recorded in 2019–2025 was 86 (Moderate), in 2019.
New Haven March air quality, year by year
New Haven March air quality by year (New Haven-Milford, CT, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019worst | 31 | 49 | 0 | 86 | PM2.5 |
| 2020cleanest | 31 | 42 | 0 | 65 | O3 |
| 2021 | 31 | 44 | 0 | 76 | PM2.5 |
| 2022 | 31 | 46 | 0 | 77 | PM2.5 |
| 2023 | 31 | 44 | 0 | 63 | O3 |
| 2024 | 31 | 42 | 0 | 55 | O3 |
| 2025 | 31 | 42 | 0 | 56 | O3 |
What March air means in New Haven
A typical March day in New Haven sits in the Good range (median AQI 43), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of March days reached AQI 101+ in 2019–2025.
March's median AQI of 43 is in line with New Haven's whole-year median of 44, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median March AQI across every EPA metro area (102,455 metro-days, 2019–2025) is 42, so New Haven runs in line with the national March norm; 0.0% of its March days topped AQI 100 versus 0.4% nationally (about the same).
March is part of New Haven's spring season (March, April, May); the spring page pools all three months.
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 month 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.