EPA's air monitors recorded unhealthy air (AQI above 100) on 37.8% of monitored days in San Bernardino County, CA from 2019 to 2023, followed by Riverside County, CA and Maricopa County, AZ, against 0.6% in the median monitored county; the years include heavy wildfire smoke.
What it shows: San Bernardino County, CA is the largest at 37.8%, followed by Riverside County, CA at 35.1%; the smallest shown is Fairbanks North Star Borough, AK at 10.3%.
Data and chart by CalcScrape: Air Filter Replacement