Indoor Air Quality and Personal Exposure Assessment Program (Indoor Program)

This page last reviewed September 20, 2017

The California Air Resources Board (ARB) carries out an Indoor Air Quality and Personal Exposure Assessment Program (Indoor Program) that includes sponsored research, regulation of air cleaning devices, exposure assessment, development of green building codes and criteria, development of indoor air quality guidelines, and public education and outreach. The goal of the Indoor Program is to improve Californians' indoor air quality and health by identifying and reducing their exposure to indoor air pollutants. The ARB is committed to pursuing actions to prevent indoor pollution and effectively reduce the significant risk it currently poses to Californians.

Ozone Generators: a Threat to Health

While many air cleaners are helpful, some are harmful because they emit ozone, a gas that can cause health problems, including respiratory tract irritation and serious lung disease. Air cleaners that emit ozone are not appropriate for home use. The ARB adopted a regulation in September 2007, which became effective in 2008, to limit ozone emissions from indoor air cleaning devices to less than 0.050 parts per million (ppm). Please visit our list of certified air cleaners and other information below.


The ARB sponsors research on indoor air quality covering topics such as indoor and personal exposure, indoor-outdoor relationships, and toxic air contaminants. ARB has funded large indoor air quality field studies in homes and schools, as well as studies on emissions from indoor sources, building ventilation, and air cleaners. Please visit our final reports for indoor air quality research.

Indoor Air Quality Report to the Legislature

Assembly Bill 1173 (Keeley), signed into law in 2002, required the Air Resources Board to prepare a comprehensive report on indoor air quality, including information on the health effects and sources of indoor pollutants; the effects of existing regulations and industry practices; and possible mitigation options for homes, schools and non-industrial workplaces. The "Report to the California Legislature: Indoor Air Pollution in California" was submitted to the Legislature in July 2005. The report identified a number of indoor air quality problems that needed to be addressed, and estimated the cost of indoor pollution in California at $45 billion per year due to premature deaths, medical costs, lost worker productivity and other costs.

Portable Classrooms Study Finds Serious Problems

The ARB and the Department of Health Services (now the Department of Public Health) conducted a comprehensive study of the environmental health conditions in portable (relocatable) classrooms. The study investigated classrooms in kindergarten through 12th grade public schools. The "Report to the Legislature on Environmental Health Conditions in California's Portable Classrooms" was submitted to the Legislature in November 2004. The study found a number of problems including inadequate ventilation, and unhealthy levels of formaldehyde and some other pollutants. The report recommended that schools meet state facility regulations, conduct self-assessments, and implement plans to remedy key indoor air quality issues, most of which can be fixed at low cost.

Education and Outreach

Indoor air quality documents, such as guidelines and fact sheets, are available via the links below. These documents identify the sources of toxic pollutants indoors and explain how you can reduce your exposure to them. The guidelines also identify safe vs. unsafe levels of pollutants for which such levels are known. The documents available are:

For further information about the program, or to order hard copies of our publications, please call our Indoor Program message line at (916) 445-0753 or write to us at:

Indoor Air Quality Program
California Air Resources Board
Research Division
P.O. Box 2815
Sacramento, CA 95812

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