Processed on 2024-03-04 12:48:57 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 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 California

January 2014 – 116 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 960 710 51 27 0 0 143
New 681 984 55 28 0 0 143

January 2015 – 136 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 854 971 63 19 0 0 139
New 644 1176 68 19 0 0 139

January 2016 – 264 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 1688 421 23 1 0 0 99
New 1396 713 21 3 0 0 99

January 2017 – 165 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2153 551 18 2 0 0 283
New 1845 858 19 2 0 0 283

January 2018 – 289 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 1728 879 61 20 0 0 71
New 1338 1268 62 20 0 0 71

January 2019 – 166 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2176 624 38 2 0 0 260
New 1840 958 40 2 0 0 260

January 2020 – 362 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2248 580 18 0 0 0 130
New 1853 974 19 0 0 0 130

January 2021 – 220 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2355 787 59 3 0 0 237
New 1940 1195 66 3 0 0 237

January 2022 – 237 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 1845 1170 68 0 0 0 265
New 1454 1553 76 0 0 0 265

January 2023 – 437 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 3300 435 2 2 0 0 167
New 2954 778 5 2 0 0 167