Harrisburg Air Quality in Fall
Across 2019–2025, Harrisburg's fall (September–November) air quality had a median AQI of 46 (Good) over 637 monitored days in the Harrisburg-Carlisle, PA area. 0.0% of fall days (0 of 637) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 73.9% of days. The cleanest fall on record here was 2025 (median AQI 40, 0 days above 100) and the worst was 2021 (median 49, 0 days above 100, peak AQI 83).
- Good: 60.0%
- Moderate: 40.0%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Harrisburg
Today's main pollutant in Harrisburg is ground-level ozone (AQI 48). 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 Harrisburg in fall?
Good on a typical day: median AQI 46 across 2019–2025, with 0.0% of fall days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓60.0% of fall days were Good (AQI 0–50), 40.0% Moderate (51–100).
- ✓0 days of 637 reached AQI 101+; the fall peak was 97.
- ✓Cleanest month: October; worst month: November.
Frequently asked questions
What is the air quality like in Harrisburg in fall?▾
Across 2019–2025, the median daily AQI in Harrisburg in fall was 46 (Good). 60.0% of days were Good, 40.0% Moderate, and 0.0% 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 Harrisburg?▾
A typical fall day in Harrisburg sits in the Good range (median AQI 46), 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 Harrisburg's fall air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 73.9% of fall days in Harrisburg. The highest fall AQI recorded in 2019–2025 was 97 (Moderate), in 2021.
Harrisburg fall air quality, year by year
Harrisburg fall air quality by year (Harrisburg-Carlisle, PA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 91 | 47 | 0 | 93 | PM2.5 |
| 2020 | 91 | 48 | 0 | 88 | PM2.5 |
| 2021worst | 91 | 49 | 0 | 83 | PM2.5 |
| 2022 | 91 | 46 | 0 | 86 | PM2.5 |
| 2023 | 91 | 43 | 0 | 94 | PM2.5 |
| 2024 | 91 | 43 | 0 | 93 | PM2.5 |
| 2025cleanest | 91 | 40 | 0 | 97 | O3 |
What fall air means in Harrisburg
A typical fall day in Harrisburg sits in the Good range (median AQI 46), 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 46 is below Harrisburg's whole-year median of 50, 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 Harrisburg runs above the national Fall norm; 0.0% of its Fall days topped AQI 100 versus 1.5% nationally (below average).
Within the season, October is the cleanest month (median AQI 43, 0.0% of days above 100) and November the worst (median 49, 0.0% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Harrisburg
The latest EPA AirNow observation puts Harrisburg's AQI at 48 (O3). The figures above are multi-year season statistics, not today's reading.
View current Harrisburg air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Harrisburg-Carlisle, PA), 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.