Air Quality

How Are We Doing?

Air quality received a thumbs down because the combined number of unhealthy air days and unhealthy air days for sensitive groups increased from 25 in 2019 to 49 in 2020. 

The number of unhealthy air days increased from 2 days in 2019 to 14 days in 2020 and for sensitive groups (people with lung disease, older adults and children) the number of unhealthy air days increased by 12 days in 2020. 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 down

Worsened more than 1 percent from 2019 to 2020


Unhealthy Days for Sensitive Groups - The 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. The total number of children's asthma hospitalizations in San Diego County decreased from 705 in 2018 to 662 in 2019. The areas of San Diego County with the highest asthma hospitalization rates in 2019, were the City of Lemon Grove, and the City of San Diego communities of Rolando Park, Linda Vista, City Heights, and Logan Heights. These are all areas whose median annual income was below that of the San Diego County 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 2021 State of the Air report,the City of San Diego ranked 7th in the nation for ozone pollution and the County of San Diego received an F for the average annual number of high ozone days.
  • 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 labor 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 County 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, the Portside Environmental Justice Neighborhoods (West National City, Barrio Logan, Logan Heights and Sherman Heights) was among the first 10 communities selected by CARB from across California as an air monitoring community. Additionally, in 2019, it was also selected to develop 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 (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, The San Diego Foundation, San Diego Association of Governments (SANDAG) and many more organizations and community leaders.

The City of San Diego and the community of San Ysidro came together to create the San Ysidro Community Air Study. Working with government officials, academic researchers, and citizen scientists, this study aims to collect neighborhood air pollution data using accessible, low-cost technology.

U.S.-Mexico Border Region

In 2019, close to 15 million vehicles crossed the U.S.-Mexico border at San Ysidro, contributing to massive air pollution and high rates of respiratory problems within this border community. 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.