What Is the Air Quality in Powell, Montana?
Powell, Montana has an Air Quality Grade of B (good) with a 5-year median AQI of 11. The dominant pollutant is Fine Particulate Matter (PM2.5), and air quality has been stable over the past decade.
Powell, Montana Air Quality Snapshot
| Air Quality Grade | B76/100 |
| 5-Year Median AQI | 11 (Good) |
| Most Recent Median AQI (2023) | 14 (Good) |
| Dominant Pollutant | Fine Particulate Matter (PM2.5) |
| 10-Year Trend | Stable (+0.21 AQI/yr) |
| Unhealthy Days (last 5 yr) | 6 |
| National Rank (cleanest = #1) | #14 of 1,020 (1th cleanest percentile) |
| Montana Rank | #2 of 19 |
What Does the B Grade Mean?
Powell, Montana earns a B — air quality is reliably in the safe range for most residents most of the time, with a 5-year median AQI of 11. Sensitive groups will see occasional caution days, but the typical resident will not need to change behavior based on air quality.
Powell, Montana's 5-year median AQI of 11 is 30 points below the national average of 41 — meaningfully cleaner than the typical U.S. metro tracked here. Within Montana, Powell, Montana runs cleaner than the state average of 31 — a positive signal that local conditions (terrain, wind patterns, emission sources) are working in residents' favor.
For context within Montana: Rosebud, Montana currently holds the state's cleanest grade (A, AQI 23), while Sanders, Montana sits at the bottom (D, AQI 36).
What's in Powell, Montana's Air?
The dominant pollutant in Powell, Montana is Fine Particulate Matter (PM2.5). Fine particulate matter — particles less than 2.5 micrometers across — comes mostly from combustion: vehicle exhaust, wildfire smoke, residential wood burning, and industrial emissions. Because these particles are small enough to enter the bloodstream, PM2.5 is the pollutant most strongly linked to cardiovascular disease, respiratory illness, and premature death.
Days by Dominant Pollutant (2023)
| Pollutant | Days as Dominant | Share of Year |
|---|---|---|
| Fine Particulate Matter (PM2.5) | 109 | 100% |
Is the Air Getting Better or Worse?
Air quality in Powell, Montana has held roughly steady over the past decade, with year-to-year shifts in median AQI of less than half a point. That stability makes the city's long-run grade a reliable signal of what residents can expect day-to-day.
In 2014, Powell, Montana posted a median AQI of 10. By 2023 that figure was 14 — a rise of 4 AQI points dirtier across 10 years of EPA records.
Year-by-Year AQI in Powell, Montana
| Year | Median AQI | Good Days | Unhealthy Days | Dominant Pollutant |
|---|---|---|---|---|
| 2014 | 10 | 110 | 1 | PM2.5 |
| 2015 | 11 | 111 | 2 | PM2.5 |
| 2016 | 10 | 116 | 0 | PM2.5 |
| 2017 | 9 | 91 | 1 | PM2.5 |
| 2018 | 12 | 104 | 0 | PM2.5 |
| 2019 | 12 | 105 | 0 | PM2.5 |
| 2020 | 3 | 33 | 0 | PM2.5 |
| 2021 | 12 | 101 | 3 | PM2.5 |
| 2022 | 12 | 105 | 1 | PM2.5 |
| 2023 | 14 | 100 | 2 | PM2.5 |
Health Context for Powell, Montana
Across the past five years, this area has logged just 6 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 1 days per year, or roughly one every other month. That is a low count by national standards.
For most healthy adults, current air quality in this area does not require any change in behavior. People with severe asthma, COPD, or recent cardiac events should still keep an eye on daily AQI alerts, especially during wildfire season. Because PM2.5 penetrates deep into the lungs and bloodstream, an N95 or KN95 mask provides meaningful protection on smoky or high-particulate days — surgical masks do not.
How This Grade Is Calculated
The AirHistory Air Quality Grade combines four signals: the 5-year median AQI (40% of the score), the 10-year trend direction (30%), the count of unhealthy days per year (20%), and the dominant pollutant type (10%). All four come directly from the EPA Air Quality System (AQS), which aggregates readings from federally certified monitors. Read the full methodology.
Powell, Montana has an Air Quality Grade of B (good) with a 5-year median AQI of 11. The dominant pollutant is Fine Particulate Matter (PM2.5), and air quality has been stable over the past decade.
The data source behind this answer is the EPA Air Quality System (AQS). Every figure on the page traces back to that source; the methodology page describes the inputs and the refresh cadence in full detail.
For readers turning this answer into action: cross-reference against the underlying the EPA Air Quality System (AQS) record before acting on time-sensitive decisions. The site renders the data as it was published; subsequent revisions can shift the picture, and the live federal data is always the authoritative current reference.
Source: EPA Outdoor Air Quality Data, 2026.