Processed on 2024-03-04 12:50:47 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 October.

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.

October in California

October 2014 – 116 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 1615 255 3 0 0 0 207
New 1269 601 3 0 0 0 207

October 2015 – 136 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 1792 292 1 1 0 0 218
New 1453 631 1 1 0 0 218

October 2016 – 264 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2165 270 1 1 0 0 251
New 1881 554 1 1 0 0 251

October 2017 – 165 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 1650 1081 65 37 0 0 271
New 1162 1564 69 35 3 0 271

October 2018 – 289 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2278 447 2 0 0 0 313
New 1806 919 2 0 0 0 313

October 2019 – 166 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2242 492 9 5 0 0 388
New 1779 954 9 6 0 0 388

October 2020 – 362 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 1539 1287 176 156 5 0 229
New 1000 1815 185 155 8 0 229

October 2021 – 220 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2787 517 53 63 4 0 288
New 2381 923 53 54 12 1 288

October 2022 – 237 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 2977 678 5 0 0 0 340
New 2306 1349 5 0 0 0 340

October 2023 – 437 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 3344 603 18 12 0 0 535
New 2732 1215 17 13 0 0 535