Processed on 2024-03-04 13:31:09 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 Montana spent in each AQI category during the the month of January.

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.

January in Montana

January 2014 – 18 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 46 47 0 0 0 0 0
New 32 61 0 0 0 0 0

January 2015 – 18 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 251 163 10 0 0 0 10
New 199 214 11 0 0 0 10

January 2016 – 36 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 245 166 23 0 0 0 0
New 198 211 25 0 0 0 0

January 2017 – 22 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 250 166 28 12 0 0 9
New 217 196 31 12 0 0 9

January 2018 – 45 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 427 119 6 2 0 0 4
New 375 171 6 2 0 0 4

January 2019 – 25 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 419 120 0 0 0 0 19
New 350 189 0 0 0 0 19

January 2020 – 46 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 476 71 1 0 0 0 10
New 437 110 1 0 0 0 10

January 2021 – 25 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 456 90 4 0 0 0 8
New 388 158 4 0 0 0 8

January 2022 – 28 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 443 141 4 0 0 0 1
New 386 198 4 0 0 0 1

January 2023 – 79 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 533 111 0 0 0 0 7
New 473 171 0 0 0 0 7