Processed on 2024-03-04 12:53:11 PST.


Disclaimer: Data presented here come from a variety of sources and do not represent official EPA measurements. Please visit AirNow for official measurements.


Cumulative exposure to smoke is an important public health metric. This report summarizes the cumulative number of days air quality monitors in Colorado spent in each AQI category during the the month of December.

The tables below include only permanent monitors measuring PM2.5 and show cumulative exposure under existing NAAQS (National Ambient Air Quality Standards) and under the 2024 revised standards for PM2.5.

In the tables and plots below, ‘Old’ designates cumulative days calculated using the 2023 PM2.5 NAAQS while ‘New’ is calculated using the 2024 revised PM2.5 NAAQS. The impact of the NAAQS revision is quite clear.

December in Colorado

December 2014 – 19 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 233 58 0 0 0 0 19
New 184 107 0 0 0 0 19

December 2015 – 19 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 215 77 1 0 0 0 48
New 180 112 1 0 0 0 48

December 2016 – 30 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 252 78 0 0 0 0 73
New 189 141 0 0 0 0 73

December 2017 – 21 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 290 76 0 0 0 0 37
New 220 146 0 0 0 0 37

December 2018 – 41 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 330 60 0 0 0 0 44
New 261 129 0 0 0 0 44

December 2019 – 20 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 310 73 1 0 0 0 19
New 256 127 1 0 0 0 19

December 2020 – 39 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 422 55 0 0 0 0 19
New 359 118 0 0 0 0 19

December 2021 – 27 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 483 24 0 0 0 0 20
New 432 75 0 0 0 0 20

December 2022 – 34 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 460 54 0 0 0 0 13
New 408 106 0 0 0 0 13

December 2023 – 147 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 284 19 0 0 0 0 147
New 256 47 0 0 0 0 147