Sheridan, Montana Air Quality
Sheridan County, Montana (MT)
→ Stableover 10 years
How Sheridan, Montana Air Quality Compares
Sheridan, Montana's median AQI of 18is 56% better than the national average of 41. The area averages 1 unhealthy air days per year. The primary pollutant of concern is Fine Particulate Matter (PM2.5).
Sheridan, Montana Air Quality: The Full Picture
Sheridan, Montana (Sheridan County) holds an AirHistory Air Quality Grade of B (good, scoring 75 out of 100), built from 10 years of EPA Air Quality System monitoring. Its median AQI rose 1 points between 2014 (17) and 2023 (18), and the five-year median now sits at 16 — inside the "Good" 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 112 of 112 monitored days (100% of the year), making it the controlling pollutant for the B grade. The single worst reading logged that year hit an AQI of 160 (Unhealthy), while the 90th-percentile day — the level the dirtiest 10% of days reach — came in at 56.
In 2023, Sheridan County recorded 96 "Good" air days (86% of the 112 days with valid AQI data), 12 "Moderate" days, and 4 days at "Unhealthy for Sensitive Groups" or above. Over the most recent five years on record, monitors logged 4 days that crossed into "Unhealthy for Sensitive Groups" or worse — about 1 per year.
The decade-long trend is essentially flat, with year-to-year median AQI shifting by less than 0.02 points per year on average. The cleanest year in the record was 2020 (median AQI 13), and the most polluted was 2018 (median AQI 20). 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).
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 | 18 | 56 | 160 | 96 | 12 | 4 | PM2.5 |
| 2022 | 16 | 36 | 66 | 85 | 4 | 0 | PM2.5 |
| 2021 | 17 | 52 | 98 | 108 | 12 | 0 | PM2.5 |
| 2020 | 13 | 27 | 58 | 103 | 4 | 0 | PM2.5 |
| 2019 | 16 | 36 | 57 | 101 | 3 | 0 | PM2.5 |
| 2018 | 20 | 52 | 118 | 99 | 12 | 1 | PM2.5 |
| 2017 | 17 | 37 | 75 | 109 | 5 | 0 | PM2.5 |
| 2016 | 15 | 31 | 81 | 113 | 4 | 0 | PM2.5 |
| 2015 | 16 | 38 | 155 | 109 | 3 | 3 | PM2.5 |
| 2014 | 17 | 42 | 74 | 109 | 5 | 0 | PM2.5 |
What This Means for Sheridan County Residents
Sheridan, Montana has received an Air Quality Grade of B (75/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 18 falls in the "Good" range.
The primary pollutant affecting this area is Fine Particulate Matter (PM2.5). Over the past 5 years, this area has averaged 1 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.
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Frequently Asked Questions
Sheridan, Montana has a current median AQI of 18, which falls in the "Good" range. The area has received an Air Quality Grade of B (75/100) based on 10 years of EPA monitoring data.
Air quality in Sheridan, Montana is stable over the past decade. The median AQI has changed by +1 points from 2014 to 2023.
Sheridan, Montana averages 1 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 Sheridan, Montana is Fine Particulate Matter (PM2.5). This is the dominant contributor to elevated AQI readings in the Sheridan County area.
Sheridan, Montana averages 1 unhealthy air days per year. This is relatively low, making it a reasonable choice for asthma sufferers. The primary pollutant is Fine Particulate Matter (PM2.5), which is a known asthma trigger.
With a median AQI of 18 (Good), outdoor exercise in Sheridan, Montana is generally safe year-round. Sheridan, Montana averages 1 days per year when athletes should move workouts indoors.