The U.S. Environmental Protection Agency (EPA) calculates and publishes an Air Quality Index (AQI) each day based on real-time monitoring by the Bay Area Air Quality Management District at a single location in San Francisco. This location monitors five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide.

Air Quality Index	Numerical Value	Meaning
Good	0 to 50	Air quality is considered satisfactory, and air pollution poses little or no risk.
Moderate	51 to 100	Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
Unhealthy for Sensitive Groups	101 to 150	Members of sensitive groups may experience health effects. The general public is not likely to be affected.
Unhealthy	151 to 200	Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.
Very Unhealthy	201 to 300	Health alert: everyone may experience more serious health effects.
Hazardous	301 to 500	Health warnings of emergency conditions. The entire population is more likely to be affected.

San Francisco's geography, local meteorology, and limited industrial activity contribute to its air quality. However, in many parts of the county, concentrations of air pollutants may exceed health-protective standards.

Improving citywide air quality is a priority because of its strong relationship to health outcomes. Poor air quality can contribute to respiratory illnesses such as aggravated asthma, chronic bronchitis, and reduced lung function. Air pollution also affects heart health and can trigger heart attacks and strokes, and air pollutants may be a contributing factor to leading causes of death recorded for San Francisco’s population. Causes include ischemic heart disease, lung, bronchus, and tracheal cancers and lower respiratory infection. Exposure to air pollutants that are carcinogens can also have significant human health consequences like lung cancer.

EPA Air Quality Rating by Year

How Performance is Measured

The EPA calculates and publishes the AQI each day based on real-time monitoring by the Bay Area Air Quality Management District at a single location on Arkansas Street in San Francisco. This location monitors five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide.

This data is being tracked as part of DPH’s Strategic Plan and staff in the Environmental Health Branch is coordinating with multiple city agencies and the Bay Area Air Quality Management District to support policies and programs that reduce emissions and human exposure to air pollution.

The number displayed on the scorecard page represents the 2022 value in the chart above.

Additional Information

Learn more about Article 38 of the San Francisco Health Code.

Data

Please click first on the chart above and then click the “Download” button in the bottom right corner of the visualization to view and download the data displayed in the chart.