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Ozone

Protecting Yourself

Children, older adults, adults who are active outdoors, and people with respiratory diseases are most likely to be harmed by high levels of ozone. Some people who don't fall into any of these categories are apparently more sensitive to ozone and also suffer problems. The best way to protect your health is to find out when ozone levels are forecasted to be elevated in your area and take simple precautions to minimize exposure, even when you do not feel obvious symptoms.

Pay attention to the air quality forecast, particularly in hot weather. The N.C. Division of Air Quality provides daily forecasts on the web at www.ncair.org/airaware/forecast. Also visit this link for information on getting the forecast by email, RSS feed, Twitter, and through EPA's "AIRNow" free smart phone app. Local weather reports and other media outlets also report the forecast. Based on the US EPA's Air Quality Index, the forecast uses an easy-to-understand color scale — with green being good and graduating colors from yellow to orange to red to purple to indicate the potential for problems. Learn more about the EPA Air Quality Index (AQI). External link

You should plan your days around these forecasts. You should also plan your children's days around these forecasts. On days when the forecast isn't good, you should minimize your exposure between 12:00 noon and 7:00 p.m., when ozone levels are highest. This is especially important for sensitive individuals. Even healthy adults should think twice about jogging in afternoons on code orange or worse days.

Air Cleaners and Indoor Ozone

The North Carolina State Health Director has issued several warnings alerting consumers that certain types of indoor air cleaners can generate potentially harmful concentrations of ozone. These air cleaning devices are known as ozone-generating air purifiers. They are also marketed as "energized or activated oxygen" or "pure air" devices.

The ozone generated by such devices is the same chemical that is responsible for the outdoor air pollution warnings issued in North Carolina during summer months. The manufacturers of ozone-generating devices provide room-sizing guidelines and some units are equipped with ozone-limiting sensors. However, controlled studies have shown that ozone concentrations from some of these devices can exceed acceptable public health standards. Independent research on ozone has shown that at concentrations below public health standards, the effectiveness of ozone to control indoor air pollutants is limited.

Also, some electronic air cleaners, such as ion generators and electrostatic precipitators, may emit low levels of ozone as a by-product. Owners should operate and maintain these air cleaners following manufacturer's instructions to reduce the potential for excess ozone generation. Any amount of ozone emitted into the indoor environment could potentially result in increased levels of reactive compounds and ultrafine particles due to reactions with fragrance compounds or other modern consumer products.

A detailed summary on the ozone generator issue External link may be found at the United States Environmental Protection Agency's (EPA) Indoor Air Quality Web Site.

The North Carolina Department of Health and Human Services (NC DHHS) has serious concerns about ozone exposures from these devices. The EPA and industrial hygienists with the NC DHHS advise the public to use other proven methods for controlling indoor air pollution. These methods include eliminating or controlling pollutant sources, increasing outdoor air ventilation, and using proven methods of air cleaning. For more information on indoor environmental quality issues, including ozone generators, please contact the Occupational and Environmental Epidemiology Branch at (919) 707-5900.

Additional Information