Ozone in Indoor Air

Ozone is a colorless gas with a noticeable smell. Although ozone is naturally found 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 breathe it in.

Health Effects of Exposure to Ozone

When breathed in, it can damage the lungs and irritate the throat. Breathing 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 asthma, bronchitis, heart disease, and emphysema may find their conditions worsen while breathing ozone.

Breathing ozone may also increase the risk of developing 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.

    Other Possible Negative Effects of Ozone

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

    Ozone Standards

    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 Food and Drug Administration has established an ozone level of 0.05 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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