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Ozone
Ozone: Helpful or Harmful?

Ozone: Helpful or Harmful? What ozone is Sources of Ozone Health problems associated with ozone Decreasing exposure to ozone Other ozone-related resources What Ozone Is Ozone is an irritating and corrosive gas that is usually colorless but becomes blue at high concentrations. It occurs naturally in the atmosphere because of thunderstorms. In the stratosphere (6 miles to 30 miles up in the air), ozone plays an important role in screening out harmful ultraviolet radiation from the sun that can result in health problems such as increased skin cancers. But down at earth level and indoors it is considered a pollutant due to emissions of nitrogen oxides and volatile organic compounds (VOCs). It can also react with VOCs in the air to produce harmful byproducts such as formaldehyde.¹ Often cities will issue air-pollution alerts when levels of ozone reach unhealthy levels. Studies have shown that people living in communities where there are high ozone levels have worse lung functions over five years than people living in communities with lower levels of ozone. These studies are consistent with animal studies, which also indicate that long-term exposure to ozone can impair lung function and cause structural changes to the lungs. Ozone is an indoor air pollutant because it is an irritant to the eyes, nose, throat and lungs. Sources of Ozone Ozone is used: To purify and disinfect drinking water To control growth of microbes and odors from industrial and municipal wastewater and sewage, swimming pools and spas, industrial processes, and fire damaged buildings As a bleaching agent To assist in making other chemicals As a food preservative In hotel and hospital air ducts and air-conditioning systems to prevent growth of biological organisms In the production of high purity silver Ozone is produced from: Photo copiers Laser printers Electric arc welding Outdoor pollution Electroplating Mercury vapor lamps X-ray generators Electrostatic air cleaners High voltage electrical equipment Indoor ultraviolet sources Health Problems Associated with Ozone There are many factors that determine if one might get sick due to exposure to ozone. These include: The concentration of ozone. Very low concentrations of ozone can be harmful to the upper respiratory tract and the lungs. The National Institle of Occupational Safety and Helath (OSHA) recommends that concentrations of 0.1 ppm of ozone never be exceeded. However, current US Environmental Protection Agency (EPA) recommendations are 0.08 ppm. Personal characteristics such as age, gender, weight, general health status. People who have preexisting lung problems, such as emphysema, bronchitis, or asthma, are even more at risk for the effects of ozone. Children also appear to be more susceptible to the effects of ozone.² Ozone can increase one's sensitivity to allergens.³ How one is exposed to ozone. Though liquid ozone can cause severe skin burns, almost all exposures are through inhalation (breathing it in). Is a person exposed to just ozone or is it a variety of pollutants? When ozone is generated in an indoor environment, it is also usually accompanied by other pollutants, such as VOCs. There is evidence that ozone increases the hazard associated with exposure to other environmental pollutants and allergens making people more susceptible to infection and decreasing their ability to get rid of inhaled particles.² How long is one exposed to ozone? The severity of injury from ozone depends on both the concentration and the duration of exposure. Severe and permanent lung injury or death could result from even a very short-term exposure to relatively low concentrations of ozone. Ozone in the presence of other low-level VOCs may produce irritating chemicals known as aldehydes. Aldehydes are strong respiratory irritants and have irritating odors at low concentrations. Health problems caused by ozone can either be acute, which occur immediately or within a few days of exposure, or they can be chronic, which are long-term health effects that last for many years. For example, repeated low-level exposure can cause long-term, and possibly permanent, lung damage. Ozone can irritate the eyes, nose, and throat. Higher exposures to ozone (0.25 ppm to 1 ppm) may result in: Cough. Shortness of breath. Tightness of the chest with a feeling of an inability to breath.e Dry throat. Wheezing. Headache. Upset stomach; nausea and/or vomiting. Reduced lung function. Pain or tightness in the chest. Extreme fatigue. Dizziness. Inability to sleep or concentrate. A bluish color to the skin due to lack of oxygen to the cells of the body (cyanosis). A build-up of fluid in the lungs (pulmonary edema). This is a medical emergency, with severe shortness of breath. This may not appear for 24 hours after exposure and can be brought on by physical exertion such as work or exercise. Occasional exposure to 9 ppm for 3 to 14 days has produced inflammation of the bronchi and lungs. Exposure to 11 ppm ozone for 15 minutes causes severe respiratory irritation and unconsciousness. A 30-minute exposure to 50 ppm or more can be deadly. Long-term health effects from exposure to extremely low concentrations of ozone include: An increase in the reactivity of the airways to other inhaled substances. There is limited evidence that ozone causes cancer in animals. It may cause lung cancer. Ozone has increased the incidence of lung tumors in laboratory mice at concentrations of 310 ppb and higher.² Genetic mutations. Damage to the developing fetus in pregnant women. Lung damage. Based on animal evidence, exposure to ozone may increase susceptibility to bacterial infections of the respiratory system. Decreasing Exposure to Ozone The best way to decrease exposure to ozone is to stay away from sources such as photocopiers and laser printers. In one study, the researchers studied the reaction to workers in an environment where there were three computers, one laser printer, and one photocopier to those of workers in a similar office without the equipment. In the office with the office machinery, peak levels of ozone were measured at 0.03 ppm with just trace amounts in the office without machinery. The researchers found that much more eye irritation in the office with the machinery as well as a worsened perception about air quality compared to the office with no machinery.⁴ Do not use ozone generators as air cleaners. The Federal Drug Administration (FDA) has said that in order for these devices to be effective, they would need to create a concentration of ozone much higher than can be safely tolerated by most people. Concentrations from ozone generators range from 0.2 ppm to 2 ppm⁵, which is high enough to produce health effects. Do not go into hotel or motel rooms right after they have been cleaned; wait at least an hour. Many hotels and motels used ozone-generating devices to clean the air in rooms after tobacco-smoking guests check out as well as in occupied rooms as a biocide and deodorizer.⁶ Stay indoors on hot, sunny days when air pollution advisories have been issued because of ozone and other atmospheric pollutants. References Ozone generators warning: not for occupied spaces. State of Alaska Epidemiology Bulletin. September 8, 1997;no. 36. Boeniger MF. Use of ozone generating devices to improve indoor air quality. American Industrial Hygiene Association Journal. 1995;56:590-598. Delfino RJ, Coate BC, Zieger RS, Seltzer JM, Street DH, Koutrakis P. Daily asthma severity in relation to personal ozone exposure and outdoor fungal spores. Am Journal Respir. Crit. Care Med. 1996;154:633-641. Wolkoff P, Johnsen CR, Franck C, Wilhardt P, Albrechtsen O. A study of human reaction of office machines in a climatic chamber. J Exp Anal Environ Epidemiol Suppl. 1992;1:71-96. Kissel JC. (1993). Potential impact of deliberately introduced ozone on indoor air quality. J Exp Anal Environ Epidemiol. 1993;3(2):155-164. Sundell J, Zuber A. Ozone and other photochemical oxidants in ambient and indoor air?properties, sources and concentrations. Scand J Work Environ Health. 1996;22(suppl 3):5-14. Other Resources The United States Environmental Protection Agency. Ozone Generators that are Sold as Air Cleaners: An Assessment of Effectiveness and Health Consequences [Online]. 2002 May 22 [accessed 2002 May 23]; Available from: http://www.epa.gov/iaq/pubs/ozonegen.html The United States Environmental Protection Agency. Ozone: Good Up High, Bad Nearby [Online]. 1997 Oct [accessed 2002 May 24]; Available from: http://www.epa.gov/oar/oaqps/gooduphigh/ Updated May 24, 2002