Lewis and Clark, Montana Air Quality
Lewis and Clark County, Montana (MT)
→ Stableover 10 years
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 | 45 | 63 | 165 | 240 | 120 | 5 | Ozone |
| 2022 | 45 | 63 | 167 | 239 | 119 | 7 | PM2.5 |
| 2021 | 44 | 77 | 156 | 249 | 99 | 17 | Ozone |
| 2020 | 42 | 60 | 168 | 277 | 84 | 5 | Ozone |
| 2019 | 43 | 68 | 144 | 251 | 112 | 2 | Ozone |
| 2018 | 46 | 67 | 169 | 238 | 117 | 10 | Ozone |
| 2017 | 47 | 93 | 177 | 209 | 127 | 29 | Ozone |
| 2016 | 42 | 58 | 146 | 281 | 78 | 7 | Ozone |
| 2015 | 44 | 69 | 178 | 254 | 98 | 13 | Ozone |
| 2014 | 42 | 65 | 150 | 268 | 92 | 5 | Ozone |
What This Means for Lewis and Clark County Residents
Lewis and Clark, Montana has received an Air Quality Grade of C (60/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 45 falls in the "Good" range.
The primary pollutant affecting this area is Ground-Level Ozone. Over the past 5 years, this area has averaged 7 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
Lewis and Clark, Montana has a current median AQI of 45, which falls in the "Good" range. The area has received an Air Quality Grade of C (60/100) based on 10 years of EPA monitoring data.
Air quality in Lewis and Clark, Montana is stable over the past decade. The median AQI has changed by +3 points from 2014 to 2023.
Lewis and Clark, Montana averages 7 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 Lewis and Clark, Montana is Ground-Level Ozone. This is the dominant contributor to elevated AQI readings in the Lewis and Clark County area.
Lewis and Clark, Montana averages 7 unhealthy air days per year. Asthma patients should monitor daily AQI readings and limit outdoor activity when AQI exceeds 100. The primary pollutant is Ground-Level Ozone, which is a known asthma trigger.
With a median AQI of 45 (Good), outdoor exercise in Lewis and Clark, Montana is generally safe year-round. Lewis and Clark, Montana averages 7 days per year when athletes should move workouts indoors.