Sioux Falls Air Quality in 2021
In 2021, Sioux Falls's air quality (Sioux Falls, SD area) had a median daily AQI of 39 (Good) across 349 monitored days. 5 days (1.4%) reached Unhealthy for Sensitive Groups or worse, 266 were Good, and the year's peak AQI was 193 (Unhealthy). Ground-level ozone set the daily AQI on 193 of those days. The cleanest month of 2021 was November (median AQI 28, 0 days above 100) and the worst was July (median 59, 3 days above 100, peak 193).
- Good: 76.2%
- Moderate: 22.3%
- Unhealthy for Sensitive Groups: 0.9%
- Unhealthy or worse: 0.6%
Reduce Indoor Ozone in Sioux Falls
Today's main pollutant in Sioux Falls is ground-level ozone (AQI 33). 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 was Sioux Falls's air quality in 2021?
Good on a typical day: median AQI 39, with 5 days above AQI 100 out of 349 monitored — the 6th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2021: 193 (Unhealthy).
- ✓Ground-level ozone was the main pollutant on 193 days.
- ✓Cleanest month: November; worst: July.
Frequently asked questions
What was the average AQI in Sioux Falls in 2021?▾
EPA's Air Quality System puts Sioux Falls's (Sioux Falls, SD) median daily AQI for 2021 at 39, which is Good. 5 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 193.
Which month had the worst air quality in Sioux Falls in 2021?▾
The cleanest month of 2021 was November (median AQI 28, 0 days above 100) and the worst was July (median 59, 3 days above 100, peak 193).
Was 2021 a good or bad year for Sioux Falls's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 6th cleanest by days above AQI 100. 2021's median of 39 is in line with the area's typical annual median of 38.
Sioux Falls month by month in 2021
Sioux Falls air quality month by month, 2021 (Sioux Falls, SD, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 33 | 0 | 77 | PM2.5 |
| February | 28 | 35 | 0 | 91 | O3 |
| March | 15 | 38 | 0 | 70 | PM2.5 |
| April | 30 | 43 | 0 | 59 | O3 |
| May | 31 | 42 | 0 | 64 | O3 |
| June | 30 | 55 | 0 | 100 | O3 |
| Julyworst | 31 | 59 | 3 | 193 | PM2.5 |
| August | 31 | 42 | 2 | 108 | PM2.5 |
| September | 30 | 41 | 0 | 59 | O3 |
| October | 31 | 30 | 0 | 61 | O3 |
| Novembercleanest | 30 | 28 | 0 | 59 | O3 |
| December | 31 | 28 | 0 | 52 | PM2.5 |
How 2021 compares
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 6th cleanest by days above AQI 100.
2021's median of 39 is in line with the area's typical annual median of 38.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Sioux Falls
The latest EPA AirNow observation puts Sioux Falls's AQI at 33 (O3). The figures above are multi-year annual statistics, not today's reading.
View current Sioux Falls air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Sioux Falls, SD), 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.