Philadelphia Air Quality in April
Across 2019–2025, Philadelphia's April air quality had a median AQI of 53 (Moderate) over 210 monitored days in the Philadelphia-Camden-Wilmington, PA-NJ-DE-MD area. 0.5% of April days (1 of 210) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 55.7% of days. The cleanest April on record here was 2019 (median AQI 48, 0 days above 100) and the worst was 2023 (median 56, 1 day above 100, peak AQI 108).
- Good: 42.4%
- Moderate: 57.1%
- Unhealthy for Sensitive Groups: 0.5%
- 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 April?
Moderate on a typical day: median AQI 53 across 2019–2025, with 0.5% of April days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓42.4% of April days were Good (AQI 0–50), 57.1% Moderate (51–100).
- ✓1 day of 210 reached AQI 101+; the April peak was 108.
- ✓Best April: 2019; worst April: 2023.
Frequently asked questions
What is the air quality like in Philadelphia in April?▾
Across 2019–2025, the median daily AQI in Philadelphia in April was 53 (Moderate). 42.4% of days were Good, 57.1% Moderate, and 0.5% reached Unhealthy for Sensitive Groups or worse, based on 210 monitored days in EPA's Air Quality System.
Is April a good time for outdoor exercise in Philadelphia?▾
A typical April day in Philadelphia is Moderate (median AQI 53): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of April days 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 April air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 55.7% of April days in Philadelphia. The highest April AQI recorded in 2019–2025 was 108 (Unhealthy for Sensitive Groups), in 2023.
Philadelphia April air quality, year by year
Philadelphia April 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 |
|---|---|---|---|---|---|
| 2019cleanest | 30 | 48 | 0 | 74 | PM2.5 |
| 2020 | 30 | 52 | 0 | 65 | PM2.5 |
| 2021 | 30 | 54 | 0 | 90 | PM2.5 |
| 2022 | 30 | 54 | 0 | 83 | PM2.5 |
| 2023worst | 30 | 56 | 1 | 108 | PM2.5 |
| 2024 | 30 | 55 | 0 | 87 | O3 |
| 2025 | 30 | 51 | 0 | 97 | O3 |
What April air means in Philadelphia
A typical April day in Philadelphia is Moderate (median AQI 53): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of April days reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
April'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 April AQI across every EPA metro area (100,677 metro-days, 2019–2025) is 44, so Philadelphia runs above the national April norm; 0.5% of its April days topped AQI 100 versus 0.7% nationally (about the same).
April is part of Philadelphia's spring season (March, April, May); the spring page pools all three months.
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 month 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.