Worcester Air Quality in October
Across 2019–2025, Worcester's October air quality had a median AQI of 34 (Good) over 217 monitored days in the Worcester, MA-CT area. 0.5% of October days (1 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 54.8% of days. The cleanest October on record here was 2025 (median AQI 30, 0 days above 100) and the worst was 2023 (median 31, 1 day above 100, peak AQI 113).
- Good: 84.3%
- Moderate: 15.2%
- Unhealthy for Sensitive Groups: 0.5%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Worcester
Today's main pollutant in Worcester 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 Worcester in October?
Good on a typical day: median AQI 34 across 2019–2025, with 0.5% of October days above AQI 100. Ground-level ozone is the main driver.
- ✓84.3% of October days were Good (AQI 0–50), 15.2% Moderate (51–100).
- ✓1 day of 217 reached AQI 101+; the October peak was 113.
- ✓Best October: 2025; worst October: 2023.
Frequently asked questions
What is the air quality like in Worcester in October?▾
Across 2019–2025, the median daily AQI in Worcester in October was 34 (Good). 84.3% of days were Good, 15.2% Moderate, and 0.5% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is October a good time for outdoor exercise in Worcester?▾
A typical October day in Worcester sits in the Good range (median AQI 34), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of October days reached AQI 101+ in 2019–2025.
Which pollutant causes Worcester's October air quality problems?▾
Ground-level ozone set the daily AQI on 54.8% of October days in Worcester. The highest October AQI recorded in 2019–2025 was 113 (Unhealthy for Sensitive Groups), in 2023.
Worcester October air quality, year by year
Worcester October air quality by year (Worcester, MA-CT, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 34 | 0 | 56 | PM2.5 |
| 2020 | 31 | 40 | 0 | 58 | PM2.5 |
| 2021 | 31 | 36 | 0 | 58 | PM2.5 |
| 2022 | 31 | 37 | 0 | 60 | PM2.5 |
| 2023worst | 31 | 31 | 1 | 113 | O3 |
| 2024 | 31 | 33 | 0 | 67 | O3 |
| 2025cleanest | 31 | 30 | 0 | 71 | O3 |
What October air means in Worcester
A typical October day in Worcester sits in the Good range (median AQI 34), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of October days reached AQI 101+ in 2019–2025.
October's median AQI of 34 is below Worcester's whole-year median of 43, making it one of the area's cleaner periods. Nationally, the median October AQI across every EPA metro area (102,872 metro-days, 2019–2025) is 38, so Worcester runs below the national October norm; 0.5% of its October days topped AQI 100 versus 1.3% nationally (about the same).
October is part of Worcester's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Worcester
The latest EPA AirNow observation puts Worcester's AQI at 32 (O3). The figures above are multi-year month 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.