Worcester Air Quality in January
Across 2019–2025, Worcester's January air quality had a median AQI of 41 (Good) over 217 monitored days in the Worcester, MA-CT area. 0.0% of January days (0 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 62.7% of days. The cleanest January on record here was 2024 (median AQI 33, 0 days above 100) and the worst was 2019 (median 51, 0 days above 100, peak AQI 62).
- Good: 67.7%
- Moderate: 32.3%
- 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 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 January?
Good on a typical day: median AQI 41 across 2019–2025, with 0.0% of January days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓67.7% of January days were Good (AQI 0–50), 32.3% Moderate (51–100).
- ✓0 days of 217 reached AQI 101+; the January peak was 88.
- ✓Best January: 2024; worst January: 2019.
Frequently asked questions
What is the air quality like in Worcester in January?▾
Across 2019–2025, the median daily AQI in Worcester in January was 41 (Good). 67.7% of days were Good, 32.3% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is January a good time for outdoor exercise in Worcester?▾
A typical January day in Worcester sits in the Good range (median AQI 41), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of January days reached AQI 101+ in 2019–2025.
Which pollutant causes Worcester's January air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 62.7% of January days in Worcester. The highest January AQI recorded in 2019–2025 was 88 (Moderate), in 2019.
Worcester January air quality, year by year
Worcester January air quality by year (Worcester, MA-CT, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019worst | 31 | 51 | 0 | 62 | PM2.5 |
| 2020 | 31 | 46 | 0 | 68 | PM2.5 |
| 2021 | 31 | 48 | 0 | 88 | PM2.5 |
| 2022 | 31 | 49 | 0 | 73 | PM2.5 |
| 2023 | 31 | 35 | 0 | 56 | PM2.5 |
| 2024cleanest | 31 | 33 | 0 | 58 | O3 |
| 2025 | 31 | 39 | 0 | 73 | O3 |
What January air means in Worcester
A typical January day in Worcester sits in the Good range (median AQI 41), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of January days reached AQI 101+ in 2019–2025.
January's median AQI of 41 is in line with Worcester's whole-year median of 43, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median January AQI across every EPA metro area (95,602 metro-days, 2019–2025) is 39, so Worcester runs in line with the national January norm; 0.0% of its January days topped AQI 100 versus 0.7% nationally (about the same).
January is part of Worcester's winter season (December, January, February); the winter 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.