Air Quality   

How are we doing?

San Diego County has the cleanest air we have ever recorded. Despite a significant increase in population and vehicle miles traveled, air quality has continually improved for decades, but it is not perfect. We strive for even more healthy days. The County’s Air Pollution Control District continues to work with industrial sources to minimize emissions and recently increased collaboration with the State of California on reducing mobile source emissions. The one parameter that affects air quality we cannot control is weather. As temperatures rise and inversion layers trap pollution, air quality deteriorates.  

How is it measured?

The federal Environmental Protection Agency (EPA) uses medical and scientific research to determine the maximum amount of air pollution that can be present and still have air quality that is considered healthy. These levels are categorized as ambient air quality standards. There are standards for ozone, particulate matter, carbon monoxide, oxides of nitrogen, oxides of sulfur and lead. The EPA is required to review these standards every five years and make adjustments based on the most recent science. Historically, these standards get tougher over time.

Healthy Air Days

Why is it important?

Pollution at unhealthy levels can cause all kinds of health issues (e.g., cardiovascular and respiratory ailments and nose, throat, eye and chest irritation) and can make conditions worse. When air pollution is bad, people do not want to go outdoors and enjoy activities.

Where are we going?

The County has achieved and maintained all the standards – except for ozone. We are getting close. The County expects to achieve the ozone standard in the next few years. We are committed to having the cleanest air possible for all residents. 

Ozone Forming Air Pollution