Processed on 2024-03-04 13:31:28 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 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 Montana

March 2014 – 18 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 49 13 0 0 0 0 0
New 41 21 0 0 0 0 0

March 2015 – 18 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 383 51 0 0 0 0 0
New 345 89 0 0 0 0 0

March 2016 – 36 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 390 36 0 0 0 0 8
New 366 60 0 0 0 0 8

March 2017 – 22 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 418 41 2 0 0 0 4
New 386 73 2 0 0 0 4

March 2018 – 45 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 461 65 0 0 0 0 1
New 410 116 0 0 0 0 1

March 2019 – 25 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 420 134 0 0 0 0 4
New 353 201 0 0 0 0 4

March 2020 – 46 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 526 27 0 0 0 0 5
New 483 70 0 0 0 0 5

March 2021 – 25 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 504 45 0 0 0 0 9
New 457 92 0 0 0 0 9

March 2022 – 28 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 557 27 0 0 0 0 5
New 526 58 0 0 0 0 5

March 2023 – 79 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 575 50 0 0 0 0 26
New 496 129 0 0 0 0 26