Allentown Best & Worst AQI Days: Air Quality Guide
The worst air quality day on record for Allentown (Allentown-Bethlehem-Easton, PA-NJ area) was June 7, 2023, when the daily AQI reached 368 (Hazardous), set by fine particulate matter (PM2.5), in wildfire smoke season. Across 2,557 monitored days in 2019–2025, 6 of the 10 worst days were Unhealthy (AQI 151+) or worse; 7 of the 10 were driven by fine particulate matter (PM2.5) and 3 by ground-level ozone, and 6 of them fell in 2023. The cleanest day was April 13, 2020 at AQI 1 (Good); the 10 best days span 4 different years.
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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When were Allentown's worst and best air quality days?
Worst: June 7, 2023, AQI 368 (Hazardous, PM2.5). Best: April 13, 2020, AQI 1 (Good). Based on 2,557 EPA-monitored days in the Allentown-Bethlehem-Easton, PA-NJ area, 2019–2025.
- ✓6 of the 10 worst days were Unhealthy (AQI 151+) or worse; the 10th-worst was AQI 119 (Unhealthy for Sensitive Groups).
- ✓Fine particulate matter (PM2.5) drove 7 of the 10 worst days.
- ✓2023 accounts for 6 of the 10 worst days.
Frequently asked questions
What was the worst air quality day in Allentown?▾
June 7, 2023: the Allentown-Bethlehem-Easton, PA-NJ area's daily AQI hit 368 (Hazardous), driven by fine particulate matter (PM2.5), in wildfire smoke season. That is the highest of 2,557 monitored days in 2019–2025.
What was the best air quality day in Allentown?▾
April 13, 2020, with a daily AQI of 1 (Good). The daily AQI is the highest reading from any monitor in the area, so even the cleanest day reflects the area's worst monitor.
What was Allentown's worst air quality day in 2025?▾
June 12, 2025, AQI 122 (Unhealthy for Sensitive Groups), set by ground-level ozone, in peak ozone season.
Which pollutant causes Allentown's worst air days?▾
Fine particulate matter (PM2.5) set the AQI on 7 of the 10 worst days; ground-level ozone on 3. The tables above list the defining pollutant for every day.
Allentown's 10 worst air quality days, 2019–2025
Highest daily AQI recorded for the Allentown-Bethlehem-Easton, PA-NJ area (EPA AQS). The daily AQI is the highest reading from any monitor in the area that day.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2023 page) | 368 | Hazardous | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 2 | (2023 page) | 199 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 3 | (2023 page) | 169 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 4 | (2023 page) | 168 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 5 | (2023 page) | 166 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 6 | (2021 page) | 154 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 7 | (2025 page) | 122 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 8 | (2024 page) | 119 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 9 | (2023 page) | 119 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 10 | (2019 page) | 119 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) |
Worst day of each year in Allentown
The single highest-AQI day in each year on record. Click a year for its full month-by-month statistics.
| Year | Worst day | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 2019 | 119 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) | |
| 2020 | 117 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) | |
| 2021 | 154 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2022 | 118 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) | |
| 2023 | 368 | Hazardous | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2024 | 119 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season | |
| 2025 | 122 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
Allentown's 10 best air quality days, 2019–2025
Lowest daily AQI recorded for the Allentown-Bethlehem-Easton, PA-NJ area. Ties are listed most recent first.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2020 page) | 1 | Good | NO2 — nitrogen dioxide |
| 2 | (2024 page) | 15 | Good | O3 — ground-level ozone |
| 3 | (2023 page) | 18 | Good | NO2 — nitrogen dioxide |
| 4 | (2025 page) | 19 | Good | O3 — ground-level ozone |
| 5 | (2024 page) | 19 | Good | O3 — ground-level ozone |
| 6 | (2024 page) | 19 | Good | O3 — ground-level ozone, in peak ozone season |
| 7 | (2023 page) | 19 | Good | O3 — ground-level ozone |
| 8 | (2023 page) | 19 | Good | O3 — ground-level ozone |
| 9 | (2023 page) | 19 | Good | O3 — ground-level ozone |
| 10 | (2020 page) | 19 | Good | O3 — ground-level ozone |
Right now in Allentown
The latest EPA AirNow observation puts Allentown's AQI at 44 (O3). The days above are historical records, 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.