Too much here ... Cars, trucks, power plants and factories all emit air pollution that forms ground-level ozone or smog. Too little there ... Many popular consumer products like air conditioners and refrigerators involve CFCs or halons during either manufacture or use. These chemicals damage the earth's protective ozone layer. http://www.epa.gov/oar/oaqps/gooduphigh/

How Can Ozone Be Both Good and Bad?

Ozone occurs in two layers of the atmosphere. The layer surrounding the earth's surface is called the troposphere. Here, ground-level or "bad" ozone is an air pollutant that damages human health, vegetation, and many common materials. It is a key ingredient of urban smog. The troposphere extends to a level about 10 miles up, where it meets the second layer, the stratosphere. The stratospheric or "good" ozone layer extends upward from about 10 to 30 miles and protects life on earth from the sun's harmful ultraviolet rays (UV-b).

What Causes "Bad" Ozone?

Motor vehicle exhaust and industrial emissions, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOC, also known as ozone precursors. Strong sunlight and hot weather cause ground-level ozone to form in harmful concentrations in the air. Many urban areas tend to have high levels of "bad" ozone, but other areas are also subject to high ozone levels as winds carry NOx emissions hundreds of miles away from their original sources.

Ozone concentrations can vary from year to year. Changing weather patterns (especially the number of hot, sunny days), periods of air stagnation, and other factors that contribute to ozone formation make long-term predictions difficult.
 

How Does "Bad" Ozone Affect Human Health and the Environment?

Repeated exposure to ozone pollution may cause permanent damage to the lungs. Even when ozone is present in low levels, inhaling it triggers a variety of health problems including chest pains, coughing, nausea, throat irritation, and congestion. It also can worsen bronchitis, heart disease, emphysema, and asthma, and reduce lung capacity.

Healthy people also experience difficulty in breathing when exposed to ozone pollution. Because ozone pollution usually forms in hot weather, anyone who spends time outdoors in the summer may be affected, particularly children, the elderly, outdoor workers and people exercising. Millions of Americans live in areas where the national ozone health standards are exceeded.

Ground-level ozone damages plant life and is responsible for 500 million dollars in reduced crop production in the United States each year. It interferes with the ability of plants to produce and store food, making them more susceptible to disease, insects, other pollutants, and harsh weather. "Bad" ozone damages the foliage of trees and other plants, ruining the landscape of cities, national parks and forests, and recreation areas .

What is Being Done About Bad Ozone?

The Clean Air Act Amendments of 1990 require EPA, states, and cities to implement programs to further reduce emissions of ozone precursors from sources such as cars, fuels, industrial facilities, power plants, and consumer/commercial products. Power plants will be reducing emissions, cleaner cars and fuels are being developed, many gas stations are using special nozzles at the pumps to recapture gasoline vapors, and vehicle inspection programs are being improved to reduce emissions.

The ultimate responsibility for our environment is our own. Minor lifestyle changes can result in major air quality improvements.

Information provided courtesy of the EPA .

What is ozone? | Why is there a difference? | How can I help?
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For more information about AACOG's Air Quality Program contact:

Peter Bella, AACOG Natural Resources Director
8700 Tesoro Drive, Suite 700
San Antonio, TX 78217
Phone: (210) 362-5249
Fax: (210) 225-5937
E-Mail: pbella@aacog.com