Ozone
Educational information. Individual clinical review of this presentation by Dr. Ehsan is not yet documented. It does not replace personal medical evaluation.
Source: MedlinePlus, National Library of Medicine. Read the original source
MedlinePlus data edition September 26, 2026. Imported September 27, 2026. These dates do not indicate a new clinical review of the article.
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. Man-made chemicals have destroyed it. 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. It can cause coughing, throat irritation, worsening of asthma, bronchitis, and emphysema. It can lead to permanent lung damage, if you are regularly exposed to it.
Environmental Protection Agency
Questions for your care team
General prompts to help prepare for your appointment.
- How does this information apply to my situation?
- Which symptoms or results need evaluation?
- Which tests are useful, and what can they tell us?
- What care options, benefits, and risks should we discuss?
- When should I seek urgent help, and whom should I call?
- When is follow-up, and how will we know whether the plan is working?
For a life-threatening emergency, call 911 in the U.S. or your local emergency number.
Browse all patient guides