Allentown Air Quality in December
Across 2019–2025, Allentown's December air quality had a median AQI of 51 (Moderate) over 217 monitored days in the Allentown-Bethlehem-Easton, PA-NJ area. 1.4% of December days (3 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 80.2% of days. The cleanest December on record here was 2023 (median AQI 39, 0 days above 100) and the worst was 2022 (median 50, 2 days above 100, peak AQI 118).
- Good: 49.3%
- Moderate: 49.3%
- Unhealthy for Sensitive Groups: 1.4%
- 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.
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How is the air in Allentown in December?
Moderate on a typical day: median AQI 51 across 2019–2025, with 1.4% of December days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓49.3% of December days were Good (AQI 0–50), 49.3% Moderate (51–100).
- ✓3 days of 217 reached AQI 101+; the December peak was 118.
- ✓Best December: 2023; worst December: 2022.
Frequently asked questions
What is the air quality like in Allentown in December?▾
Across 2019–2025, the median daily AQI in Allentown in December was 51 (Moderate). 49.3% of days were Good, 49.3% Moderate, and 1.4% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is December a good time for outdoor exercise in Allentown?▾
A typical December day in Allentown is Moderate (median AQI 51): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 71 of December days (1.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Allentown's December air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 80.2% of December days in Allentown. The highest December AQI recorded in 2019–2025 was 118 (Unhealthy for Sensitive Groups), in 2022.
Allentown December air quality, year by year
Allentown December 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 | 31 | 51 | 0 | 98 | PM2.5 |
| 2020 | 31 | 53 | 1 | 117 | PM2.5 |
| 2021 | 31 | 55 | 0 | 82 | PM2.5 |
| 2022worst | 31 | 50 | 2 | 118 | PM2.5 |
| 2023cleanest | 31 | 39 | 0 | 89 | PM2.5 |
| 2024 | 31 | 46 | 0 | 76 | PM2.5 |
| 2025 | 31 | 39 | 0 | 89 | PM2.5 |
What December air means in Allentown
A typical December day in Allentown is Moderate (median AQI 51): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 71 of December days (1.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
December's median AQI of 51 is above Allentown's whole-year median of 46, making it one of the area's dirtier periods. Nationally, the median December AQI across every EPA metro area (95,590 metro-days, 2019–2025) is 39, so Allentown runs above the national December norm; 1.4% of its December days topped AQI 100 versus 0.7% nationally (about the same).
December is part of Allentown's winter season (December, January, February); the winter page pools all three months.
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 month 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.