Ozone is a gas. It can be good or bad, depending on where it is. "Good" ozone occurs naturally about 10 to 30 miles above the Earth's surface. It shields us from the sun's ultraviolet rays. Part of the good ozone layer is gone - destroyed by man-made chemicals. Without enough good ozone, people may get too much ultraviolet radiation. This may increase the risk of skin cancer, cataracts and immune system problems.
"Bad" ozone is at ground level. It forms when pollutants from cars, factories and other sources react chemically with sunlight. It is the main ingredient in smog. It is usually worst in the summer. Breathing bad ozone can be harmful, causing coughing, throat irritation, worsening of asthma, bronchitis and emphysema, and even permanent lung damage, if you are regularly exposed to it.
Environmental Protection Agency
Also available in Spanish
Also available in Spanish
Basics | Learn More | Multimedia & Cool Tools |
---|---|---|
Research | Reference Shelf | For You |
Also available in Spanish
References and abstracts from MEDLINE/PubMed (National Library of Medicine)
Also available in Spanish
Also available in Spanish
Home | Health Topics | Drugs & Supplements | Encyclopedia | Dictionary | News | Directories | Other Resources | |
Disclaimers | Copyright | Privacy | Accessibility | Quality Guidelines U.S. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894 National Institutes of Health | Department of Health & Human Services |
Date last updated: 07 January 2009 Topic last reviewed: 05 August 2008 |