Boston Air Quality in 2023
In 2023, Boston's air quality (Boston-Cambridge-Newton, MA-NH area) had a median daily AQI of 50 (Good) across 365 monitored days. 7 days (1.9%) reached Unhealthy for Sensitive Groups or worse, 190 were Good, and the year's peak AQI was 136 (Unhealthy for Sensitive Groups). Fine particulate matter (PM2.5) set the daily AQI on 229 of those days. The cleanest month of 2023 was November (median AQI 35, 0 days above 100) and the worst was June (median 59, 3 days above 100, peak 136).
- Good: 52.1%
- Moderate: 46.0%
- Unhealthy for Sensitive Groups: 1.9%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Boston
Today's main pollutant in Boston is ground-level ozone (AQI 28). 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 was Boston's air quality in 2023?
Good on a typical day: median AQI 50, with 7 days above AQI 100 out of 365 monitored — the 7th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2023: 136 (Unhealthy for Sensitive Groups).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 229 days.
- ✓Cleanest month: November; worst: June.
Frequently asked questions
What was the average AQI in Boston in 2023?▾
EPA's Air Quality System puts Boston's (Boston-Cambridge-Newton, MA-NH) median daily AQI for 2023 at 50, which is Good. 7 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 136.
Which month had the worst air quality in Boston in 2023?▾
The cleanest month of 2023 was November (median AQI 35, 0 days above 100) and the worst was June (median 59, 3 days above 100, peak 136).
Was 2023 a good or bad year for Boston's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2023 ranks 7th cleanest by days above AQI 100 — the worst year on record here. 2023's median of 50 is in line with the area's typical annual median of 48.
Boston month by month in 2023
Boston air quality month by month, 2023 (Boston-Cambridge-Newton, MA-NH, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 49 | 0 | 65 | PM2.5 |
| February | 28 | 53 | 0 | 74 | PM2.5 |
| March | 31 | 48 | 0 | 60 | PM2.5 |
| April | 30 | 52 | 2 | 119 | O3 |
| May | 31 | 50 | 0 | 87 | O3 |
| Juneworst | 30 | 59 | 3 | 136 | O3 |
| July | 31 | 54 | 1 | 114 | PM2.5 |
| August | 31 | 49 | 0 | 66 | PM2.5 |
| September | 30 | 50 | 0 | 81 | PM2.5 |
| October | 31 | 33 | 1 | 102 | PM2.5 |
| Novembercleanest | 30 | 35 | 0 | 60 | PM2.5 |
| December | 31 | 42 | 0 | 71 | PM2.5 |
How 2023 compares
Among the 7 years EPA has published for the area (2019–2025), 2023 ranks 7th cleanest by days above AQI 100 — the worst year on record here.
2023's median of 50 is in line with the area's typical annual median of 48.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Boston
The latest EPA AirNow observation puts Boston's AQI at 28 (O3). The figures above are multi-year annual statistics, not today's reading.
View current Boston 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.