Knoxville Air Quality in Winter
Across 2019–2025, Knoxville's winter (December–February) air quality had a median AQI of 50 (Good) over 632 monitored days in the Knoxville, TN area. 0.0% of winter days (0 of 632) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 78.2% of days. The cleanest winter on record here was 2019 (median AQI 47, 0 days above 100) and the worst was 2022 (median 53, 0 days above 100, peak AQI 73).
- Good: 50.2%
- Moderate: 49.8%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Knoxville
Today's main pollutant in Knoxville is ground-level ozone (AQI 36). 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 Knoxville in winter?
Good on a typical day: median AQI 50 across 2019–2025, with 0.0% of winter days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓50.2% of winter days were Good (AQI 0–50), 49.8% Moderate (51–100).
- ✓0 days of 632 reached AQI 101+; the winter peak was 79.
- ✓Cleanest month: February; worst month: December.
Frequently asked questions
What is the air quality like in Knoxville in winter?▾
Across 2019–2025, the median daily AQI in Knoxville in winter was 50 (Good). 50.2% of days were Good, 49.8% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 632 monitored days in EPA's Air Quality System.
Is winter a good time for outdoor exercise in Knoxville?▾
A typical winter day in Knoxville sits in the Good range (median AQI 50), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of winter days reached AQI 101+ in 2019–2025.
Which pollutant causes Knoxville's winter air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 78.2% of winter days in Knoxville. The highest winter AQI recorded in 2019–2025 was 79 (Moderate), in 2022.
Knoxville winter air quality, year by year
Knoxville winter air quality by year (Knoxville, TN, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 90 | 47 | 0 | 68 | PM2.5 |
| 2020 | 91 | 49 | 0 | 74 | PM2.5 |
| 2021 | 90 | 53 | 0 | 79 | PM2.5 |
| 2022worst | 90 | 53 | 0 | 73 | PM2.5 |
| 2023 | 90 | 52 | 0 | 75 | PM2.5 |
| 2024 | 91 | 47 | 0 | 79 | PM2.5 |
| 2025 | 90 | 49 | 0 | 66 | PM2.5 |
What winter air means in Knoxville
A typical winter day in Knoxville sits in the Good range (median AQI 50), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of winter days reached AQI 101+ in 2019–2025.
Winter's median AQI of 50 is in line with Knoxville's whole-year median of 52, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median Winter AQI across every EPA metro area (278,620 metro-days, 2019–2025) is 40, so Knoxville runs above the national Winter norm; 0.0% of its Winter days topped AQI 100 versus 0.6% nationally (about the same).
Within the season, February is the cleanest month (median AQI 48, 0.0% of days above 100) and December the worst (median 52, 0.0% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Knoxville
The latest EPA AirNow observation puts Knoxville's AQI at 36 (O3). The figures above are multi-year season statistics, not today's reading.
View current Knoxville air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Knoxville, TN), 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.