Ozone and Air Quality


What is ozone?

Ozone is a colorless gas with a noticeable odor. When inhaled, it can damage the lungs and irritate the throat.

Although ozone is found and is naturally produced in the atmosphere, it is also a main part of air pollution called smog. In the upper layer of the sky, ozone is helpful in protecting us from some of the effects of the sun. However, when it exists in the lower layer, close to the earth (outdoors and in our homes), it can be harmful if we inhale it.

The use of some equipment, such as certain types of “air cleaning” devices, can cause increased levels of ozone in homes or work settings.

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What are the possible health effects of breathing ozone?

Inhaling fairly low amounts of ozone can result in signs and symptoms such as coughing, congestion, wheezing, shortness of breath, and chest pain in otherwise healthy people. People with already existing asthma, bronchitis, heart disease, and emphysema may find their conditions worsen while inhaling ozone.

Breathing ozone may also increase the risk of getting certain lung diseases. People can recover from short-term exposure to low levels of ozone. However, breathing high levels of ozone or breathing low levels of ozone over a long period of time may have more damaging and longer-lasting effects.

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Are there other possible negative effects of ozone?

Although some manufacturers of air cleaning equipment have claimed that ozone generators can decrease volatile organic compounds (VOCs) in the air, research has shown that such devices may, in fact, increase some types of VOCS.

If an air cleaning device produces ozone at a level that is effective in killing molds and viruses, then it is also at a level that can be harmful to human beings and pets.

(For information on VOCs, see our Fact Sheet on Volatile Organic Compounds.)

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What are possible sources of ozone in my home, school or workplace?

Ozone can be released into the air from some office equipment such as laser printers and copiers, from some types of “air cleaners” such as some electric or ion generators, and from certain industrial processes such as ozone treatment of bottled water.

What factors contribute to the amount of ozone I inhale?

If ozone is present in a home, school or workplace, there are several factors that may affect the amount of ozone that a person inhales:

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Can I test my home, school or workplace for ozone?

Unless you have a likely source for ozone in the indoor setting, AND unless you have some possible signs and symptoms of ozone exposure, testing the indoor air for ozone is not likely to be helpful, informative, or needed. Rather than focusing your attention and finances on testing the air, try to improve air quality by using other fairly low cost options.

Are there standards for ozone?

There are national standards relating to the amount of ozone that certain types of equipment or devices may produce and there are standards for workplace exposure. In addition, the U.S. Food and Drug Administration has established an ozone level of .05 ppm (parts per million) as the maximum level allowable in an enclosed space intended to be occupied by people for extended periods of time. This includes homes, apartments and offices.

The standards for industrial settings are different and are set and enforced by other agencies such as the Vermont Occupational Safety and Health Administration and the American Conference of Governmental Industrial Hygienists.

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What can I do to reduce the risk of being exposed to ozone in my home, school or workplace?

There are several steps you can take to reduce or eliminate risks from ozone.

Where can I get more information?

Please see our Indoor Air Quality Resource Guide.

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