Ozone (O3)


Ozone (O3) is the major harmful ingredient in smog. It is not emitted directly into the air but produced in the atmosphere when gases or vapors of organic chemicals called hydrocarbons combine with nitrogen oxide compounds in the presence of sunlight. Organic hydrocarbon gases, one of the raw ingredients of ozone, are released from a variety of sources related to human activities. Major sources include refineries, gas stations, motor vehicles, chemical plants, paints and solvents. Harmful ozone in the lower atmosphere should not be confused with ozone in the upper atmosphere, which protects us from ultraviolet radiation.

Ozone near the ground can cause a number of health problems. Ozone can lead to more frequent asthma attacks in people who have asthma and can cause sore throats, coughs, and breathing difficulty. It may even lead to premature death. Ozone can also hurt plants and crops.

Health effects: Ozone reacts with lung tissue. It can inflame and cause harmful changes in breathing passages, decrease the lungs' working ability and cause both coughing and chest pains. Ozone air pollution, found at unhealthful levels in nearly all of the nation's major urban areas, may particularly affect millions of otherwise healthy Americans who, for currently unknown 1reason, are especially sensitive to it. People who exercise are also more vulnerable to the effects of ozone, suffering symptoms and a reduced ability to breathe at relatively low ozone levels. Ozone pollution, even at low levels, has also been linked to increased hospital admissions and emergency room visits for respiratory problems.