Processed on 2024-03-04 12:51:44 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 March.

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.

March in Colorado

March 2014 – 19 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 242 19 0 0 0 0 80
New 221 40 0 0 0 0 80

March 2015 – 19 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 207 28 2 0 0 0 73
New 185 50 2 0 0 0 73

March 2016 – 30 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 294 8 0 0 0 0 39
New 274 28 0 0 0 0 39

March 2017 – 21 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 331 31 0 0 0 0 41
New 306 56 0 0 0 0 41

March 2018 – 41 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 370 8 0 0 0 0 25
New 346 32 0 0 0 0 25

March 2019 – 20 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 341 63 10 2 0 0 18
New 288 116 10 2 0 0 18

March 2020 – 39 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 393 18 0 0 0 0 54
New 349 62 0 0 0 0 54

March 2021 – 27 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 432 37 9 1 0 0 48
New 382 86 10 1 0 0 48

March 2022 – 34 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 473 19 0 0 0 0 35
New 430 62 0 0 0 0 35

March 2023 – 147 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 423 34 0 0 0 0 39
New 376 81 0 0 0 0 39