Big Stone Colony, Montana Air Quality
Big Stone Colony has a median AQI of 46, earning an air quality grade of B+ — good air quality that ranks better than 25% of US cities. Air quality has been trending worse over the past decade, a concern for local residents and health officials. Particulate matter (PM2.5) is the primary concern, often linked to vehicle traffic, industrial activity, and wildfire smoke. In 2024, Big Stone Colony recorded 52 good air quality days (60% of monitored days).
Population: 45 • County: Cascade
Current AQI
Quick Facts
| Current AQI | 59 — Moderate |
| Air Quality Grade | B+ |
| Median AQI (2024) | 46 |
| vs. U.S. Cities | Better than 25% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 0 |
| 10-Year Trend | ↓ Worsening |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is acceptable. However, there may be a risk for some people who are unusually sensitive to air pollution.
Unusually sensitive people should consider reducing prolonged or heavy outdoor exertion.
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for Big Stone Colony is sourced from the Great Falls monitoring area, located approximately 8 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 Big Stone Colony'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
Big Stone Colony Median AQI by Year
Annual EPA air quality data for Big Stone Colony — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2024 | 46 | 52 | — | 74 | PM2.5 |
| 2023 | 50 | 176 | 6 | 170 | PM2.5 |
| 2022 | 23 | 323 | 2 | 128 | PM2.5 |
| 2021 | 27 | 296 | 11 | 160 | PM2.5 |
| 2020 | 24 | 314 | 3 | 115 | PM2.5 |
| 2019 | 28 | 326 | 1 | 106 | PM2.5 |
| 2018 | 33 | 303 | 6 | 166 | PM2.5 |
| 2017 | 38 | 241 | 1 | 105 | PM2.5 |
| 2016 | 33 | 319 | — | 75 | PM2.5 |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2024 Air Quality Summary
Primary Pollutant Days (2024)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About Big Stone Colony Air Quality
What is the air quality in Big Stone Colony today?
The current AQI in Big Stone Colony is 59, rated "Moderate". Air quality is moderate — unusually sensitive individuals may want to limit prolonged outdoor exertion. Air quality is acceptable. However, there may be a risk for some people who are unusually sensitive to air pollution.
Is air quality in Big Stone Colony getting better or worse?
Air quality in Big Stone Colony has been worsening. The median AQI has risen 13 points (from 33 in 2016 to 46 in 2024), a concern for local health officials.
What is the most common air pollutant in Big Stone Colony?
PM2.5 is the primary air pollutant in Big Stone Colony, responsible for 87 days (100% of monitored days) in 2024. Particulate matter originates from vehicle exhaust, wildfires, construction, and industrial activity.
How many unhealthy air days does Big Stone Colony have per year?
In 2024, Big Stone Colony recorded 60% good air quality days (52 days) out of 87 monitored days. There were 0 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 74.
What air quality grade does Big Stone Colony receive?
Big Stone Colony receives an air quality grade of B+, placing it better than 25% of US cities. This is based on a median AQI of 46 in 2024, with 52 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 25% of US cities
Nearby Cities
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National Rankings
See how Big Stone Colony compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Big Stone Colony
Big Stone Colony 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.
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