Cambridge Air Quality in March
Across 2019–2025, Cambridge's March air quality had a median AQI of 45 (Good) over 217 monitored days in the Boston-Cambridge-Newton, MA-NH 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 49.8% of days. The cleanest March on record here was 2024 (median AQI 41, 0 days above 100) and the worst was 2019 (median 53, 0 days above 100, peak AQI 66).
- Good: 69.1%
- Moderate: 30.9%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Cambridge
Today's main pollutant in Cambridge is ground-level ozone (AQI 33). 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 Cambridge in March?
Good on a typical day: median AQI 45 across 2019–2025, with 0.0% of March days above AQI 100. Ground-level ozone is the main driver.
- ✓69.1% of March days were Good (AQI 0–50), 30.9% Moderate (51–100).
- ✓0 days of 217 reached AQI 101+; the March peak was 77.
- ✓Best March: 2024; worst March: 2019.
Frequently asked questions
What is the air quality like in Cambridge in March?▾
Across 2019–2025, the median daily AQI in Cambridge in March was 45 (Good). 69.1% of days were Good, 30.9% 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 Cambridge?▾
A typical March day in Cambridge sits in the Good range (median AQI 45), 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 Cambridge's March air quality problems?▾
Ground-level ozone set the daily AQI on 49.8% of March days in Cambridge. The highest March AQI recorded in 2019–2025 was 77 (Moderate), in 2019.
Cambridge March air quality, year by year
Cambridge March air quality by year (Boston-Cambridge-Newton, MA-NH, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019worst | 31 | 53 | 0 | 66 | PM2.5 |
| 2020 | 31 | 44 | 0 | 60 | PM2.5 |
| 2021 | 31 | 47 | 0 | 77 | PM2.5 |
| 2022 | 31 | 51 | 0 | 67 | PM2.5 |
| 2023 | 31 | 48 | 0 | 60 | PM2.5 |
| 2024cleanest | 31 | 41 | 0 | 60 | O3 |
| 2025 | 31 | 45 | 0 | 61 | O3 |
What March air means in Cambridge
A typical March day in Cambridge sits in the Good range (median AQI 45), 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 45 is in line with Cambridge's whole-year median of 48, 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 Cambridge 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 Cambridge's spring season (March, April, May); the spring page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Cambridge
The latest EPA AirNow observation puts Cambridge's AQI at 33 (O3). The figures above are multi-year month statistics, not today's reading.
View current Cambridge air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Boston-Cambridge-Newton, MA-NH), 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.