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 EPA monitoring data. 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.