Worcester Air Quality in 2020
In 2020, Worcester's air quality (Worcester, MA-CT area) had a median daily AQI of 43 (Good) across 366 monitored days. 0 days (0.0%) reached Unhealthy for Sensitive Groups or worse, 256 were Good, and the year's peak AQI was 90 (Moderate). Fine particulate matter (PM2.5) set the daily AQI on 233 of those days. The cleanest month of 2020 was September (median AQI 37, 0 days above 100) and the worst was August (median 52, 0 days above 100, peak 84).
- Good: 69.9%
- Moderate: 30.1%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Worcester
Today's main pollutant in Worcester is ground-level ozone (AQI 31). 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 Worcester's air quality in 2020?
Good on a typical day: median AQI 43, with 0 days above AQI 100 out of 366 monitored — the 1st cleanest of 7 years on record for the area.
- ✓Peak AQI in 2020: 90 (Moderate).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 233 days.
- ✓Cleanest month: September; worst: August.
Frequently asked questions
What was the average AQI in Worcester in 2020?▾
EPA's Air Quality System puts Worcester's (Worcester, MA-CT) median daily AQI for 2020 at 43, which is Good. 0 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 90.
Which month had the worst air quality in Worcester in 2020?▾
The cleanest month of 2020 was September (median AQI 37, 0 days above 100) and the worst was August (median 52, 0 days above 100, peak 84).
Was 2020 a good or bad year for Worcester's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2020 ranks 1st cleanest by days above AQI 100 — the best year on record here. 2020's median of 43 is in line with the area's typical annual median of 43.
Worcester month by month in 2020
Worcester air quality month by month, 2020 (Worcester, MA-CT, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 46 | 0 | 68 | PM2.5 |
| February | 29 | 48 | 0 | 65 | PM2.5 |
| March | 31 | 43 | 0 | 57 | O3 |
| April | 30 | 44 | 0 | 55 | O3 |
| May | 31 | 42 | 0 | 67 | O3 |
| June | 30 | 47 | 0 | 87 | O3 |
| July | 31 | 51 | 0 | 90 | PM2.5 |
| Augustworst | 31 | 52 | 0 | 84 | PM2.5 |
| Septembercleanest | 30 | 37 | 0 | 74 | PM2.5 |
| October | 31 | 40 | 0 | 58 | PM2.5 |
| November | 30 | 42 | 0 | 67 | PM2.5 |
| December | 31 | 41 | 0 | 63 | PM2.5 |
How 2020 compares
Among the 7 years EPA has published for the area (2019–2025), 2020 ranks 1st cleanest by days above AQI 100 — the best year on record here.
2020'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 Worcester
The latest EPA AirNow observation puts Worcester's AQI at 31 (O3). The figures above are multi-year annual statistics, not today's reading.
View current Worcester air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Worcester, MA-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.