Boulder, Colorado Air Quality
Boulder County, Colorado (CO)
↑ Worseningover 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 in this area has been declining over the past 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 | 50 | 74 | 181 | 192 | 167 | 6 | Ozone |
| 2022 | 47 | 77 | 129 | 224 | 134 | 7 | Ozone |
| 2021 | 52 | 100 | 160 | 154 | 176 | 35 | Ozone |
| 2020 | 51 | 84 | 181 | 173 | 172 | 21 | Ozone |
| 2019 | 50 | 74 | 119 | 192 | 168 | 5 | Ozone |
| 2018 | 49 | 96 | 159 | 198 | 135 | 29 | Ozone |
| 2017 | 46 | 80 | 149 | 233 | 113 | 11 | Ozone |
| 2016 | 39 | 52 | 97 | 178 | 26 | 0 | Ozone |
| 2015 | 44 | 71 | 129 | 253 | 105 | 7 | Ozone |
| 2014 | 45 | 71 | 126 | 254 | 101 | 5 | Ozone |
What This Means for Boulder County Residents
Boulder, Colorado has received an Air Quality Grade of D (48/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 50 falls in the "Good" range.
Concerning trends show air quality has been declining, with the median AQI rising by 5 points over the monitoring period. This could be driven by increased development, wildfire smoke, or industrial activity.
The primary pollutant affecting this area is Ground-Level Ozone. 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 Colorado
Frequently Asked Questions
Boulder, Colorado has a current median AQI of 50, which falls in the "Good" range. The area has received an Air Quality Grade of D (48/100) based on 10 years of EPA monitoring data.
Air quality in Boulder, Colorado is worsening over the past decade. The median AQI has changed by +5 points from 2014 to 2023.
Boulder, Colorado 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 Boulder, Colorado is Ground-Level Ozone. This is the dominant contributor to elevated AQI readings in the Boulder County area.
Boulder, Colorado 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 Ground-Level Ozone, which is a known asthma trigger.
With a median AQI of 50 (Good), outdoor exercise in Boulder, Colorado is generally safe year-round. Boulder, Colorado averages 15 days per year when athletes should move workouts indoors.