Processed on 2024-03-04 12:49:21 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 California 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 California

March 2014 – 116 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 1571 224 0 2 0 0 94
New 1266 529 0 2 0 0 94

March 2015 – 136 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 1675 286 3 0 0 0 113
New 1342 619 3 0 0 0 113

March 2016 – 264 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 1933 167 2 1 0 0 129
New 1708 392 2 1 0 0 129

March 2017 – 165 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2370 363 8 1 1 0 171
New 1981 751 9 1 1 0 171

March 2018 – 289 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2388 258 1 0 0 0 143
New 2099 546 2 0 0 0 143

March 2019 – 166 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2683 138 0 0 0 0 186
New 2471 350 0 0 0 0 186

March 2020 – 362 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2742 108 1 0 0 0 125
New 2567 283 1 0 0 0 125

March 2021 – 220 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 3059 195 2 0 0 0 154
New 2673 581 2 0 0 0 154

March 2022 – 237 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2994 263 2 0 0 0 213
New 2582 675 2 0 0 0 213

March 2023 – 437 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 3548 129 0 0 0 0 229
New 3293 384 0 0 0 0 229