Worcester Air Quality in July
Across 2019–2025, Worcester's July air quality had a median AQI of 50 (Good) over 217 monitored days in the Worcester, MA-CT area. 1.4% of July days (3 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 59.4% of days. The cleanest July on record here was 2024 (median AQI 44, 0 days above 100) and the worst was 2021 (median 52, 2 days above 100, peak AQI 125).
- Good: 50.2%
- Moderate: 48.4%
- Unhealthy for Sensitive Groups: 1.4%
- 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 July?
Good on a typical day: median AQI 50 across 2019–2025, with 1.4% of July days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓50.2% of July days were Good (AQI 0–50), 48.4% Moderate (51–100).
- ✓3 days of 217 reached AQI 101+; the July peak was 145.
- ✓Best July: 2024; worst July: 2021.
Frequently asked questions
What is the air quality like in Worcester in July?▾
Across 2019–2025, the median daily AQI in Worcester in July was 50 (Good). 50.2% of days were Good, 48.4% Moderate, and 1.4% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is July a good time for outdoor exercise in Worcester?▾
A typical July day in Worcester sits in the Good range (median AQI 50), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 71 of July days (1.4%) reached AQI 101+ in 2019–2025.
Which pollutant causes Worcester's July air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 59.4% of July days in Worcester. The highest July AQI recorded in 2019–2025 was 145 (Unhealthy for Sensitive Groups), in 2021.
Worcester July air quality, year by year
Worcester July 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 | 55 | 0 | 97 | PM2.5 |
| 2020 | 31 | 51 | 0 | 90 | PM2.5 |
| 2021worst | 31 | 52 | 2 | 125 | PM2.5 |
| 2022 | 31 | 53 | 0 | 100 | PM2.5 |
| 2023 | 31 | 50 | 1 | 145 | PM2.5 |
| 2024cleanest | 31 | 44 | 0 | 84 | O3 |
| 2025 | 31 | 44 | 0 | 91 | O3 |
What July air means in Worcester
A typical July day in Worcester sits in the Good range (median AQI 50), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 71 of July days (1.4%) reached AQI 101+ in 2019–2025.
July's median AQI of 50 is above Worcester's whole-year median of 43, making it one of the area's dirtier periods. Nationally, the median July AQI across every EPA metro area (103,858 metro-days, 2019–2025) is 47, so Worcester runs in line with the national July norm; 1.4% of its July days topped AQI 100 versus 3.6% nationally (below average).
July is part of Worcester's summer season (June, July, August); the summer 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.