Missoula, Montana Air Quality
Missoula County, Montana (MT)
↓ Improvingover 10 years
How Missoula, Montana Air Quality Compares
Missoula, Montana's median AQI of 53is 29% worse than the national average of 41. Residents experience an average of 15 unhealthy air days per year, above the national threshold for concern. The primary pollutant of concern is Fine Particulate Matter (PM2.5).
Missoula, Montana Air Quality: The Full Picture
Missoula, Montana (Missoula County) holds an AirHistory Air Quality Grade of C (fair, scoring 54 out of 100), built from 10 years of EPA Air Quality System monitoring. Its median AQI rose 1 points between 2014 (52) and 2023 (53), and the five-year median now sits at 54 — inside the "Moderate" band on the EPA scale.
The pollutant driving most of the area's AQI readings is Fine Particulate Matter (PM2.5). In 2023, it set the daily AQI on 297 of 364 monitored days (82% of the year), making it the controlling pollutant for the C grade. The single worst reading logged that year hit an AQI of 134 (Unhealthy for Sensitive Groups), while the 90th-percentile day — the level the dirtiest 10% of days reach — came in at 76.
In 2023, Missoula County recorded 156 "Good" air days (43% of the 364 days with valid AQI data), 200 "Moderate" days, and 8 days at "Unhealthy for Sensitive Groups" or above. Over the most recent five years on record, monitors logged 76 days that crossed into "Unhealthy for Sensitive Groups" or worse — about 15 per year.
The decade-long trend is improving: median AQI has been dropping by roughly 0.30 points per year. The cleanest year in the record was 2014 (median AQI 52), and the most polluted was 2017 (median AQI 65). Because the data come straight from federally certified EPA monitors, these figures track the Montana county the monitors physically sit in rather than a city boundary.
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10-Year AQI Trend
The solid line shows the median AQI each year. The dashed line shows the 90th percentile (worst 10% of days). This area has seen measurable air quality improvement over the decade.
Air Quality Day Breakdown
Number of days per year in each EPA AQI category. Green = Good (AQI 0-50), Yellow = Moderate (51-100), Orange = Unhealthy for Sensitive Groups (101-150), Red = Unhealthy or worse (151+).
Year-by-Year Data
| Year | Median AQI | 90th Pct | Max AQI | Good Days | Moderate | Unhealthy+ | Pollutant |
|---|---|---|---|---|---|---|---|
| 2023 | 53 | 76 | 134 | 156 | 200 | 8 | PM2.5 |
| 2022 | 54 | 81 | 190 | 149 | 201 | 15 | PM2.5 |
| 2021 | 56 | 94 | 162 | 122 | 213 | 30 | PM2.5 |
| 2020 | 54 | 85 | 185 | 155 | 192 | 19 | PM2.5 |
| 2019 | 52 | 78 | 153 | 173 | 188 | 4 | PM2.5 |
| 2018 | 54 | 80 | 154 | 146 | 215 | 4 | PM2.5 |
| 2017 | 65 | 185 | 1130 | 52 | 240 | 73 | PM2.5 |
| 2016 | 58 | 96 | 139 | 72 | 269 | 25 | PM2.5 |
| 2015 | 56 | 92 | 209 | 126 | 216 | 23 | PM2.5 |
| 2014 | 52 | 87 | 159 | 173 | 174 | 18 | PM2.5 |
What This Means for Missoula County Residents
Missoula, Montana has received an Air Quality Grade of C (54/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 53 falls in the "Moderate" range.
Encouragingly, air quality here has been improving, with the median AQI dropping by 1 points over the monitoring period. This trend suggests continued investment in emission controls and cleaner energy.
The primary pollutant affecting this area is Fine Particulate Matter (PM2.5). Over the past 5 years, this area has averaged 15 unhealthy air quality days per year, days when sensitive groups (children, elderly, those with respiratory conditions) should limit outdoor activity. The American Lung Association's State of the Air report provides additional context on long-term health risks from air pollution exposure.
Related Cities in Montana
Frequently Asked Questions
Missoula, Montana has a current median AQI of 53, which falls in the "Moderate" range. The area has received an Air Quality Grade of C (54/100) based on 10 years of EPA monitoring data.
Air quality in Missoula, Montana is improving over the past decade. The median AQI has changed by +1 points from 2014 to 2023.
Missoula, Montana averages 15 unhealthy air quality days per year over the past 5 years. On these days, sensitive groups including children, the elderly, and those with respiratory conditions should limit outdoor activity.
The primary pollutant affecting Missoula, Montana is Fine Particulate Matter (PM2.5). This is the dominant contributor to elevated AQI readings in the Missoula County area.
Missoula, Montana averages 15 unhealthy air days per year. Asthma patients should monitor daily AQI readings and limit outdoor activity when AQI exceeds 100. The primary pollutant is Fine Particulate Matter (PM2.5), which is a known asthma trigger.
With a median AQI of 53 (Moderate), outdoor exercise in Missoula, Montana is safe most days, though sensitive individuals should check daily AQI before intense workouts. Missoula, Montana averages 15 days per year when athletes should move workouts indoors.