SAN BERNARDINO COUNTY SEES GRADUAL AIR QUALITY IMPROVEMENT OVER PAST 10 YEARS
Poor air quality can aggravate the symptoms of heart and lung ailments, including asthma. It can also cause irritation and illness among the healthy population. Long-term exposure increases the risks of lung cancer, cardiovascular disease, and many other health conditions. Poor air quality can also put children’s lung development at risk. This indicator uses the Air Quality Index (AQI) to measure air quality in San Bernardino County, neighboring California counties, and peer regions outside of California.
TREND
The most common air quality status for San Bernardino County is the “moderate” range. In 2025, more than half of the days in the year (57%) were in the “moderate” range. Since 2016, the percentage of days in the “unhealthy for sensitive groups” range has declined while the percentage days in the “good” range has increased. The median AQI value, where a higher value represents poorer air quality, improved in 2025 compared to the 10-year high in 2020 (77 and 93, respectively). Both values are in the “moderate” range.
Air Quality Index Key
| Index Value | Name | Advisory |
|---|---|---|
| 0 to 50 | Good | None |
| 51 to 100 | Moderate | Unusually sensitive individuals should consider limiting prolonged outdoor exertion |
| 101 to 150 | Unhealthy for Sensitive Groups | Children, active adults and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion |
| 151 to 200 | Unhealthy | Children, active adults and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else should limit prolonged outdoor exertion |
| 201 to 300 | Very Unhealthy | Children, active adults and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else should limit outdoor exertion |
| 301 to 500 | Hazardous | Everyone should avoid all physical activity outdoors |
PERCENTAGE OF DAYS WITH “GOOD” AIR QUALITY ON UPWARD TREND
Percentage of Days When Air Quality Index Was Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy or Hazardous in San Bernardino County, 2016-2025
GEOGRAPHIC COMPARISON
Within peer regions, there is variation in the number of days each region experiences in the six AQI categories – from “good” to “hazardous.” However, the median AQI value, which takes into account all daily AQI readings in a given year, was poorer in San Bernardino County in 2025 than all regions compared except Riverside County and the Phoenix metro area. Over the past 10 years, San Bernardino County’s median air quality value has remained within the three highest among the regions compared.
SAN BERNARDINO MEDIAN AIR QUALITY HEALTHIER THAN RIVERSIDE AND PHOENIX IN 2025
Number of Days When the Air Quality Index was Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy or Hazardous, Regional Comparison, 2025