Air Quality

How Are We Doing?

Air quality received a thumbs up because the combined number of unhealthy air days and unhealthy air days for sensitive groups decreased from 35 in 2018 to 25 in 2019. The total number of children's asthma hospitalizations in San Diego County decreased from 705 in 2018 to 662 in 2019. 

The number of unhealthy air days for sensitive groups (people with lung disease, older adults and children) decreased by 12 days in 2019, while unhealthy air days increased from 0 days in 2018 to 2 days in 2019. Overall, air quality figures are the lowest they have been since 2010. Note that the daily air quality rating is based on the worst monitoring results among 18 stations throughout San Diego County. 

Want to know more about what we're measuring?

thumbs up

Improved more than 1 percent from 2018 to 2019


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.

Poor air quality is known to significantly increase the risk of asthma attacks and subsequent hospitalizations. Asthma is a preventable disease that disproportionately affects populations with a low socio-economic status. In 2018, the areas with the highest asthma hospitalization rates were Lemon Grove, College Grove, Linda Vista, City Heights, and Logan Heights, all neighborhoods whose median annual income was below that of the San Diego region. 

Search the map to see how hospitalization rates from asthma in children differ among zip codes across the San Diego region. Toggle to the menu bar in the top left corner to check out more features of this map. 

*Data not available for all zip codes 

  • Environment: Air quality is important due to the short- and long-term effects on public health. Measures of air quality reflect air pollution caused by industrial, commercial facilities and individual use of fossil fuels especially for transportation. According to the American Lung Association’s 2020 State of the Air report, the City of San Diego ranked 6th in the nation and the County of San Diego ranked 8th in the nation in terms of ozone pollution.
  • Economy: The economic consequences of air pollution are substantial and are expected to worsen over the next 40 years. Poor air quality negatively affects the economy through reduced labour productivity, increased health expenditures, and crop yield losses.
  • Equity: Communities that have higher cumulative environmental burdens are home to 90% of the worst air pollution in the San Diego region. These communities also have high concentrations of poverty and residents are predominantly people of color.

Regional Response


In response to AB 617, the California Air Resource Board (CARB) launched the Community Air Protection Program (CAPP) to address toxic emissions and community air monitoring. The legislation also provides funding and grants to support clean technologies and community engagement as well as higher fees and greater transparency in terms of air quality and emission data.


In 2018, Portside Environmental Justice Neighborhoods (West National City, Barrio Logan, Logan Heights and Sherman Heights) was among the first 10 communities in all of California selected by CARB for air monitoring community. Additionally, in 2019, it was selected for a Community Emissions Reduction Plan (CERP). Its steering committee consists of community residents and groups as well as local businesses who work closely with the Air Pollution Control District to strategically improve air quality.


San Diegans come together each year to participate in Clean Air Day which is supported by numerous government agencies, San Diego Gas & Electric, San Diego Foundation, SANDAG and many more organizations and community leaders.

U.S.-Mexico Border Region

In 2019, close to 15 million vehicles crossed the U.S.-Mexico border at San Ysidro, leading to massive air pollution and high rates of respiratory problems. A multi-year research project involving the University of Washington, the California Office of Environmental Health Hazard Assessment, and the community organization, Casa Familiar, is tackling this problem by installing air quality monitors and tracking pollution data, which can be used to develop effective pollution mitigation programs.

What Are We Measuring?

We measure air quality by tracking the number of days when San Diego County’s air is considered unhealthy or very unhealthy for the total population as well as when it is unhealthy for sensitive groups as recorded in the EPA Air Quality Index Report. Air pollution levels measured at a particular monitoring site are not necessarily representative of the air quality for an entire county or urban area. We also measure children’s asthma hospitalization rates by ZIP code throughout the county and report on those areas with 5 or more events. Learn more about the data.