Billings Air Quality in 2025
In 2025, Billings's air quality (Billings, MT area) had a median daily AQI of 38 (Good) across 365 monitored days. 0 days (0.0%) reached Unhealthy for Sensitive Groups or worse, 315 were Good, and the year's peak AQI was 91 (Moderate). Ground-level ozone set the daily AQI on 220 of those days. The cleanest month of 2025 was January (median AQI 28, 0 days above 100) and the worst was September (median 46, 0 days above 100, peak 91).
- Good: 86.3%
- Moderate: 13.7%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Billings
Today's main pollutant in Billings is ground-level ozone (AQI 21). 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 Billings's air quality in 2025?
Good on a typical day: median AQI 38, with 0 days above AQI 100 out of 365 monitored — the 1st cleanest of 6 years on record for the area.
- ✓Peak AQI in 2025: 91 (Moderate).
- ✓Ground-level ozone was the main pollutant on 220 days.
- ✓Cleanest month: January; worst: September.
Frequently asked questions
What was the average AQI in Billings in 2025?▾
EPA's Air Quality System puts Billings's (Billings, MT) median daily AQI for 2025 at 38, which is Good. 0 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 91.
Which month had the worst air quality in Billings in 2025?▾
The cleanest month of 2025 was January (median AQI 28, 0 days above 100) and the worst was September (median 46, 0 days above 100, peak 91).
Was 2025 a good or bad year for Billings's air?▾
Among the 6 years EPA has published for the area (2020–2025), 2025 ranks 1st cleanest by days above AQI 100 — the best year on record here. 2025's median of 38 is in line with the area's typical annual median of 38.
Billings month by month in 2025
Billings air quality month by month, 2025 (Billings, MT, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| Januarycleanest | 31 | 28 | 0 | 55 | PM2.5 |
| February | 28 | 41 | 0 | 77 | PM2.5 |
| March | 31 | 38 | 0 | 45 | O3 |
| April | 30 | 40 | 0 | 54 | O3 |
| May | 31 | 43 | 0 | 84 | O3 |
| June | 30 | 46 | 0 | 85 | O3 |
| July | 31 | 42 | 0 | 88 | O3 |
| August | 31 | 38 | 0 | 57 | O3 |
| Septemberworst | 30 | 46 | 0 | 91 | PM2.5 |
| October | 31 | 30 | 0 | 41 | O3 |
| November | 30 | 28 | 0 | 77 | O3 |
| December | 31 | 32 | 0 | 59 | PM2.5 |
How 2025 compares
Among the 6 years EPA has published for the area (2020–2025), 2025 ranks 1st cleanest by days above AQI 100 — the best year on record here.
2025's median of 38 is in line with the area's typical annual median of 38.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Billings
The latest EPA AirNow observation puts Billings's AQI at 21 (O3). The figures above are multi-year annual statistics, not today's reading.
View current Billings air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Billings, MT), 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.