Allentown Air Quality in Fall
Across 2019–2025, Allentown's fall (September–November) air quality had a median AQI of 41 (Good) over 637 monitored days in the Allentown-Bethlehem-Easton, PA-NJ area. 0.2% of fall days (1 of 637) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 64.5% of days. The cleanest fall on record here was 2025 (median AQI 37, 0 days above 100) and the worst was 2021 (median 47, 0 days above 100, peak AQI 72).
- Good: 69.2%
- Moderate: 30.6%
- Unhealthy for Sensitive Groups: 0.2%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Allentown
Today's main pollutant in Allentown 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 Allentown in fall?
Good on a typical day: median AQI 41 across 2019–2025, with 0.2% of fall days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓69.2% of fall days were Good (AQI 0–50), 30.6% Moderate (51–100).
- ✓1 day of 637 reached AQI 101+; the fall peak was 101.
- ✓Cleanest month: October; worst month: September.
Frequently asked questions
What is the air quality like in Allentown in fall?▾
Across 2019–2025, the median daily AQI in Allentown in fall was 41 (Good). 69.2% of days were Good, 30.6% Moderate, and 0.2% 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 Allentown?▾
A typical fall day in Allentown 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 fall days reached AQI 101+ in 2019–2025.
Which pollutant causes Allentown's fall air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 64.5% of fall days in Allentown. The highest fall AQI recorded in 2019–2025 was 101 (Unhealthy for Sensitive Groups), in 2021.
Allentown fall air quality, year by year
Allentown fall air quality by year (Allentown-Bethlehem-Easton, PA-NJ, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 91 | 39 | 0 | 77 | PM2.5 |
| 2020 | 91 | 42 | 0 | 99 | PM2.5 |
| 2021worst | 91 | 47 | 0 | 72 | PM2.5 |
| 2022 | 91 | 44 | 0 | 85 | PM2.5 |
| 2023 | 91 | 41 | 0 | 69 | PM2.5 |
| 2024 | 91 | 36 | 1 | 101 | O3 |
| 2025cleanest | 91 | 37 | 0 | 89 | O3 |
What fall air means in Allentown
A typical fall day in Allentown 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 fall days reached AQI 101+ in 2019–2025.
Fall's median AQI of 41 is below Allentown's whole-year median of 46, making it one of the area's cleaner periods. Nationally, the median Fall AQI across every EPA metro area (296,275 metro-days, 2019–2025) is 40, so Allentown runs in line with the national Fall norm; 0.2% of its Fall days topped AQI 100 versus 1.5% nationally (below average).
Within the season, October is the cleanest month (median AQI 37, 0.0% of days above 100) and September the worst (median 41, 0.5% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Allentown
The latest EPA AirNow observation puts Allentown's AQI at 44 (O3). The figures above are multi-year season statistics, not today's reading.
View current Allentown air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Allentown-Bethlehem-Easton, PA-NJ), 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.