Processed on 2024-03-04 13:21:28 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 Massachusetts 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 Massachusetts

March 2014 – 9 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 206 59 0 0 0 0 14
New 149 116 0 0 0 0 14

March 2015 – 9 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 232 47 0 0 0 0 0
New 179 100 0 0 0 0 0

March 2016 – 20 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 233 32 0 0 0 0 14
New 223 42 0 0 0 0 14

March 2017 – 10 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 264 2 0 0 0 0 13
New 251 15 0 0 0 0 13

March 2018 – 24 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 274 8 0 0 0 0 28
New 251 31 0 0 0 0 28

March 2019 – 14 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 362 36 0 0 0 0 36
New 278 120 0 0 0 0 36

March 2020 – 28 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 410 16 0 0 0 0 8
New 348 78 0 0 0 0 8

March 2021 – 17 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 418 35 0 0 0 0 12
New 364 89 0 0 0 0 12

March 2022 – 17 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 462 62 0 0 0 0 3
New 364 160 0 0 0 0 3

March 2023 – 19 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 497 24 0 0 0 0 37
New 440 81 0 0 0 0 37