Cambridge Air Quality in Spring
Across 2019–2025, Cambridge's spring (March–May) air quality had a median AQI of 45 (Good) over 644 monitored days in the Boston-Cambridge-Newton, MA-NH area. 0.3% of spring days (2 of 644) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 60.2% of days. The cleanest spring on record here was 2024 (median AQI 43, 0 days above 100) and the worst was 2023 (median 48, 2 days above 100, peak AQI 119).
- Good: 69.7%
- Moderate: 30.0%
- Unhealthy for Sensitive Groups: 0.3%
- 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 spring?
Good on a typical day: median AQI 45 across 2019–2025, with 0.3% of spring days above AQI 100. Ground-level ozone is the main driver.
- ✓69.7% of spring days were Good (AQI 0–50), 30.0% Moderate (51–100).
- ✓2 days of 644 reached AQI 101+; the spring peak was 119.
- ✓Cleanest month: May; worst month: April.
Frequently asked questions
What is the air quality like in Cambridge in spring?▾
Across 2019–2025, the median daily AQI in Cambridge in spring was 45 (Good). 69.7% of days were Good, 30.0% Moderate, and 0.3% reached Unhealthy for Sensitive Groups or worse, based on 644 monitored days in EPA's Air Quality System.
Is spring a good time for outdoor exercise in Cambridge?▾
A typical spring 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 spring days reached AQI 101+ in 2019–2025.
Which pollutant causes Cambridge's spring air quality problems?▾
Ground-level ozone set the daily AQI on 60.2% of spring days in Cambridge. The highest spring AQI recorded in 2019–2025 was 119 (Unhealthy for Sensitive Groups), in 2023.
Cambridge spring air quality, year by year
Cambridge spring 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 |
|---|---|---|---|---|---|
| 2019 | 92 | 45 | 0 | 69 | O3 |
| 2020 | 92 | 44 | 0 | 60 | PM2.5 |
| 2021 | 92 | 46 | 0 | 100 | O3 |
| 2022 | 92 | 46 | 0 | 70 | O3 |
| 2023worst | 92 | 48 | 2 | 119 | PM2.5 |
| 2024cleanest | 92 | 43 | 0 | 93 | O3 |
| 2025 | 92 | 45 | 0 | 84 | O3 |
What spring air means in Cambridge
A typical spring 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 spring days reached AQI 101+ in 2019–2025.
Spring'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 Spring AQI across every EPA metro area (307,196 metro-days, 2019–2025) is 43, so Cambridge runs in line with the national Spring norm; 0.3% of its Spring days topped AQI 100 versus 0.8% nationally (about the same).
Within the season, May is the cleanest month (median AQI 44, 0.0% of days above 100) and April the worst (median 46, 1.0% above 100).
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 season 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.