Philadelphia Air Quality in Fall
Across 2019–2025, Philadelphia's fall (September–November) air quality had a median AQI of 53 (Moderate) over 637 monitored days in the Philadelphia-Camden-Wilmington, PA-NJ-DE-MD area. 1.1% of fall days (7 of 637) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 81.2% of days. The cleanest fall on record here was 2025 (median AQI 48, 0 days above 100) and the worst was 2023 (median 55, 3 days above 100, peak AQI 107).
- Good: 37.7%
- Moderate: 61.2%
- Unhealthy for Sensitive Groups: 1.1%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Philadelphia
Today's main pollutant in Philadelphia is ground-level ozone (AQI 44). 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 Philadelphia in fall?
Moderate on a typical day: median AQI 53 across 2019–2025, with 1.1% of fall days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓37.7% of fall days were Good (AQI 0–50), 61.2% Moderate (51–100).
- ✓7 days of 637 reached AQI 101+; the fall peak was 143.
- ✓Cleanest month: October; worst month: November.
Frequently asked questions
What is the air quality like in Philadelphia in fall?▾
Across 2019–2025, the median daily AQI in Philadelphia in fall was 53 (Moderate). 37.7% of days were Good, 61.2% Moderate, and 1.1% reached Unhealthy for Sensitive Groups or worse, based on 637 monitored days in EPA's Air Quality System.
Is fall a good time for outdoor exercise in Philadelphia?▾
A typical fall day in Philadelphia is Moderate (median AQI 53): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 91 of fall days (1.1%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Philadelphia's fall air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 81.2% of fall days in Philadelphia. The highest fall AQI recorded in 2019–2025 was 143 (Unhealthy for Sensitive Groups), in 2023.
Philadelphia fall air quality, year by year
Philadelphia fall air quality by year (Philadelphia-Camden-Wilmington, PA-NJ-DE-MD, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 91 | 53 | 1 | 105 | PM2.5 |
| 2020 | 91 | 53 | 2 | 143 | PM2.5 |
| 2021 | 91 | 55 | 0 | 88 | PM2.5 |
| 2022 | 91 | 54 | 0 | 76 | PM2.5 |
| 2023worst | 91 | 55 | 3 | 107 | PM2.5 |
| 2024 | 91 | 51 | 1 | 104 | PM2.5 |
| 2025cleanest | 91 | 48 | 0 | 93 | PM2.5 |
What fall air means in Philadelphia
A typical fall day in Philadelphia is Moderate (median AQI 53): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 91 of fall days (1.1%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Fall's median AQI of 53 is in line with Philadelphia's whole-year median of 56, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median Fall AQI across every EPA metro area (296,275 metro-days, 2019–2025) is 40, so Philadelphia runs above the national Fall norm; 1.1% of its Fall days topped AQI 100 versus 1.5% nationally (about the same).
Within the season, October is the cleanest month (median AQI 52, 0.5% of days above 100) and November the worst (median 56, 1.4% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Philadelphia
The latest EPA AirNow observation puts Philadelphia's AQI at 44 (O3). The figures above are multi-year season statistics, not today's reading.
View current Philadelphia air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Philadelphia-Camden-Wilmington, PA-NJ-DE-MD), 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.