Profiles of Innovative State Programs: California - Limiting Ozone from Indoor Air Cleaners

The Indoor Exposure Assessment Program of the California Air Resources Board (ARB) conducts research on and assesses exposure to indoor air pollutants, educates the public on indoor air hazards, and develops IAQ guidelines. Following passage of a state law, the ARB adopted a regulation making California the first state to limit ozone emissions from indoor air cleaning devices in order to protect public health. As part of this regulatory initiative, the ARB has developed a considerable amount of information on the subject that can be used by people throughout the U.S. to reduce their indoor exposure to ozone.

Why is this Project Important?

Exposure to ozone can produce a number of harmful health effects, including damage to airway tissues, asthma exacerbation, and risk of premature death in susceptible populations. Some air cleaning devices intentionally emit ozone. According to the ARB, scientific research shows that ozone is ineffective at removing or reducing other indoor pollutants, while increasing the health risks of those who use ozone-generating air purifiers—an estimated 500,000 people in California alone. Agency research showed that indoor air cleaning devices which intentionally emit ozone may quickly expose household members to ozone levels that are several times the outdoor air quality standard for the pollutant.

What Materials and Resources Have Been Developed Under the Project?

The Air Resources Board has a web page on "Hazardous Ozone-Generating ‘Air Purifiers’” that offers a wealth of information, including a link to a list of indoor air cleaning devices that are certified to meet ARB’s ozone emissions limits, a list of ozone generators to avoid, and agency research on air purifiers that generate ozone. The web page also provides a link to the ARB Air Cleaner Regulation page, which contains information on the regulation for manufacturers of indoor air purifiers and the public, including a short fact sheet titled “California’s Regulation to Limit Ozone Emissions from Indoor Air Cleaning Devices.”

How Can You Learn More?

Visit the ARB's “Hazardous Ozone-Generating ‘Air Purifiers’” webpage and the main program page.