Processed on 2024-03-04 13:32:03 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 June.

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.

June in Montana

June 2014 – 18 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 90 0 0 0 0 0 3
New 89 1 0 0 0 0 3

June 2015 – 18 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 401 9 1 1 0 0 22
New 345 65 1 0 1 0 22

June 2016 – 36 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 403 15 0 0 0 0 16
New 372 46 0 0 0 0 16

June 2017 – 22 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 431 20 1 0 0 0 75
New 397 54 1 0 0 0 75

June 2018 – 45 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 478 8 0 0 0 0 41
New 472 14 0 0 0 0 41

June 2019 – 25 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 485 17 0 0 0 0 56
New 463 39 0 0 0 0 56

June 2020 – 46 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 502 10 0 0 0 0 46
New 496 16 0 0 0 0 46

June 2021 – 25 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 486 13 0 0 0 0 59
New 443 56 0 0 0 0 59

June 2022 – 28 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 543 5 0 0 0 0 41
New 532 16 0 0 0 0 41

June 2023 – 79 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 609 46 0 0 0 0 27
New 535 120 0 0 0 0 27