Dewey, Montana Air Quality
Dewey has a median AQI of 12, earning an air quality grade of A+ — excellent air quality that ranks better than 97% of US cities. Air quality has remained relatively stable over the past decade. Particulate matter (PM2.5) is the primary concern, often linked to vehicle traffic, industrial activity, and wildfire smoke. In 2025, Dewey recorded 175 good air quality days (100% of monitored days).
Population: 26 • County: Beaverhead
Current AQI
Quick Facts
| Current AQI | 19 — Good |
| Air Quality Grade | A+ |
| Median AQI (2025) | 12 |
| vs. U.S. Cities | Better than 97% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 0 |
| 10-Year Trend | → Stable |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is satisfactory, and air pollution poses little or no risk.
It's a great day to be active outside!
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for Dewey is sourced from the Butte monitoring area, located approximately 23 miles from city center. This EPA-certified station continuously tracks particulate matter (PM2.5), the primary driver of air quality alerts in this area.
Wildfire smoke is a significant factor in Dewey's air quality, with regional fires capable of pushing AQI from Good to Unhealthy within hours during fire season (typically July through October). On smoke-impacted days, staying indoors with windows closed and running an air purifier with a HEPA filter is the most effective protection.
AQI Trend (10 Years)
Air Quality Days by Year
Dewey Median AQI by Year
Annual EPA air quality data for Dewey — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 12 | 175 | — | 48 | PM2.5 |
| 2024 | 12 | 298 | 2 | 180 | PM2.5 |
| 2023 | 13 | 344 | 2 | 124 | PM2.5 |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2025 Air Quality Summary
Primary Pollutant Days (2025)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About Dewey Air Quality
What is the air quality in Dewey today?
The current AQI in Dewey is 19, rated "Good". Air quality is good — outdoor activity is safe for everyone today. Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in Dewey getting better or worse?
Air quality in Dewey has been stable. The median AQI has dropped 1 points (from 13 in 2023 to 12 in 2025).
What is the most common air pollutant in Dewey?
PM2.5 is the primary air pollutant in Dewey, responsible for 175 days (100% of monitored days) in 2025. Particulate matter originates from vehicle exhaust, wildfires, construction, and industrial activity.
How many unhealthy air days does Dewey have per year?
In 2025, Dewey recorded 100% good air quality days (175 days) out of 175 monitored days. There were 0 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 48.
What air quality grade does Dewey receive?
Dewey receives an air quality grade of A+, placing it better than 97% of US cities. This is based on a median AQI of 12 in 2025, with 175 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 97% of US cities
Nearby Cities
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National Rankings
See how Dewey compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Dewey
Dewey faces elevated PM2.5 from wildfire smoke in addition to year-round traffic and industrial sources. We prioritize True HEPA units with high smoke CADR — essential for rapid air cleaning during smoke events.
Blueair Blue Pure 211+
High performance for large rooms with simple operation.
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Other Great Options
Molekule Air Pro
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Honeywell HPA300
Powerful workhorse for large rooms. Built to last.
Coway Airmega AP-1512HH
Best overall value for medium rooms. Excellent performance at an affordable price.
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