Unhealthy Days for Sensitive Groups - General public is not likely to be affected but people with lung disease, older adults and children are at a greater risk.
Unhealthy Days - Everyone may begin to experience some adverse health effects, and members of the sensitive groups may experience more serious effects.
Very Unhealthy Days - This triggers a health alert signifying that everyone may experience more serious health effects.
In 2017, total unhealthy air days for all groups increased from 42 days in 2016 to 62 days. The number of unhealthy air days for sensitive groups (people with lung disease, older adults and children) increased by 16 days in 2017, while unhealthy air days increased by 4 days and very unhealthy air days remained at zero. Note that the daily air quality rating is based on the worst monitoring results among 18 stations throughout San Diego County. While unhealthy air quality days fell significantly from 2008 to 2010, the numbers have increased during the past few years.
*2017 data is preliminary.
Data Sources: U.S. Environmental Protection Agency, Air Quality Index Report, 2018