Air Pollution - Ozone

Average daily maximum concentration (parts per billion) of ground-level ozone throughout a month

Source:
George Mason University.
266026.1
Dashboard-City Average

Why do we measure ozone?

Ozone is an air pollutant linked to poor respiratory health outcomes, including diminished lung function, emergency room visits for asthma, hospital admissions, and premature deaths.1,2 Ozone in the ambient air is created by chemical reactions between pollutants such as nitrogen oxides and volatile organic compounds that are released by cars, power plants, and chemical plants, as well as by natural sources such as trees and soils. These reactions occur under sunlight and more efficiently on hot days. As a result, ground-level ozone pollution is most likely to reach unhealthy levels in the summer.3

In 2020, the United States Environmental Protection Agency (EPA) determined that ozone levels higher than 70 parts per billion (ppb) can cause health problems for otherwise healthy adults while they engage in outdoor activities.4,5 Cities can reduce the impacts of ground-level ozone on residents’ health by adopting clean energy sources, improving use of public transportation, ensuring that fireplace and wood stove use meets EPA standards, and through other actions.6

How do we measure ozone?

The Dashboard’s ozone metric shows the average daily maximum 8-hour concentration of ozone in the air (in ppb) over the course of a month.

Strengths and Limitations

Strengths of Metric

Limitations of Metric

• Monitoring air quality helps target high pollution areas and track progress in reducing pollution, which can lower the risk of mortality.7

• This metric provides the most geographically granular, up-to-date, publicly available data for ozone air pollution.

• The measure is estimated using data from a network of sensors around the country. It is less accurate in areas with fewer sensors.

• Data for Alaska and Hawaii are not currently available.

• Due to limited geographic resolution, census tracts that are right next to each other might share the same ozone pollution value. Please refer to our technical document for more details.

Calculation

For more information on the calculation, please refer to the City Health Dashboard Technical Document.

Data Source

The data were created by merging ground observations from the US Environmental Protection Agency (EPA) Air Quality System (AQS) network with computer model prediction from the National Oceanic and Atmospheric Administration (NOAA) National Air Quality Forecast Capability (NAQFC) by the George Mason University air quality team. Multi-year data are available for this metric. For more information, please refer to Using Multi-Year Data: Tips and Cautions. 

Years of Collection

Calculated by the Dashboard Team using data from December 2023, 1 month average estimate.

References

  1. Centers of Disease Control and Prevention. Air pollution. https://www.cdc.gov/climateandhealth/effects/air_pollution.htm

  2. United States Environmental Protection Agency. Ground-level Ozone Pollution. https://www.epa.gov/ground-level-ozone-pollution

  3. United States Environmental Protection Agency. Ground-level Ozone Basics. https://www.epa.gov/ground-level-ozone-pollution/ground-level-ozone-basics#wwh

  4. FACT SHEET: FINAL DECISION OZONE NATIONAL AMBIENT AIR QUALITY STANDARDS (2020).

  5. OVERVIEW OF EPA’S UPDATES TO THE AIR QUALITY STANDARDS FOR GROUND-LEVEL OZONE (2015).

  6. Agency USEP. What You Can Do. https://www.airnow.gov/education/what-you-can-do/

  7. Jerrett M, Burnett RT, Pope CA, et al. Long-Term Ozone Exposure and Mortality. New England Journal of Medicine. 2009;360(11):1085-1095. doi:10.1056/NEJMoa0803894

Last updated: July 26, 2023