Ozone is a colorless gas that can be found
in the upper atmosphere about 20 to 30 miles above the earth where it acts
as a protective shield. Ozone prevents some of the sun's cancer-causing ultraviolet rays (rays with a wavelength between that of
visible light and x-rays) from reaching the earth's surface. But when ozone
forms near the surface of the earth, it can be harmful. If ozone is breathed
in, it reacts with the tissues of the lung and can cause symptoms. When ozone
levels are high, individuals with asthma often experience a harder time breathing,
may have more asthma attacks, and need to use more medications. The October
8, 2003, issue of JAMA includes an article on the
health effects of ozone among children with asthma.
Ozone is formed through chemical reactions involving hydrocarbons and nitrogen oxide (types of
pollution) and sunlight on calm summer days. Ozone peaks in the middle of
the day throughout the summer months and is worse in cities with high levels
of pollution or smog. Children who spend lots of time playing outside, persons
with asthma, and elderly individuals are most at risk of the effects of ozone.
Irritation of the eyes, nose, and throat
Difficulty taking a deep breath
Increased need for asthma medications
Minimize your exposure to ozone by staying indoors during peak
ozone hours, usually afternoons on sunny summer days.
If you exercise outside, minimize your ozone exposure by exercising
before 11 AM or after 8 PM.
Listen to your local weather report for "ozone action days" days
that exceed safe levels of ozone. Try to stay inside as much as possible on
ozone action days.
US Environmental Protection Agency http://www.epa.gov
American Lung Association 212/315-8700 http://www.lungusa.org
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Sources: US Environmental Protection Agency, American Lung Association,
United Nations Environment Program
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Parmet S, Lynm C, Glass RM. Health Effects of Ozone. JAMA. 2003;290(14):1944. doi:10.1001/jama.290.14.1827