Processed on 2024-03-04 12:52:51 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 October.

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.

October in Colorado

October 2014 – 19 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 304 4 0 0 0 0 12
New 294 14 0 0 0 0 12

October 2015 – 19 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 271 39 0 0 0 0 42
New 237 73 0 0 0 0 42

October 2016 – 30 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 327 11 0 0 0 0 14
New 283 55 0 0 0 0 14

October 2017 – 21 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 342 20 1 0 0 0 53
New 295 67 1 0 0 0 53

October 2018 – 41 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 361 30 0 0 0 0 57
New 327 64 0 0 0 0 57

October 2019 – 20 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 352 24 0 0 0 0 72
New 330 46 0 0 0 0 72

October 2020 – 39 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 310 148 19 2 0 0 33
New 240 218 19 2 0 0 33

October 2021 – 27 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 504 9 0 0 0 0 31
New 465 48 0 0 0 0 31

October 2022 – 34 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 490 21 0 0 0 0 33
New 454 57 0 0 0 0 33

October 2023 – 147 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 444 26 0 0 0 0 74
New 415 55 0 0 0 0 74