Skip to main content


What is it?

Ozone is a gas that occurs both in the earth’s upper atmosphere and at the earth’s ground level. In the upper atmosphere, ozone protects life on earth from the sun’s harmful ultraviolet rays.

Ozone on the ground level is the main ingredient of smog. It is formed when sunlight reacts with pollution from vehicles, power plants, and industrial sources. Ozone pollution is worse in the afternoon and early evening.

Ozone can also be manufactured. It is used to purify air and drinking water, control mold and bacteria, and disinfect laundry in commercial settings.

See also: Factories Gas Station Power Plants Vehicles and Engines Air Pollution

Where is Ozone found?

  • Air – smog, emissions from vehicles, power plants, and industrial sources
  • Consumer products – some air and water purifiers

How can I be exposed to Ozone?

Ozone commonly enter(s) the body through:

Inhalation (breathing)
  • Breathing polluted air, especially smog in the summer
Skin contact
  • Touching water purifiers or water treated with ozone

What happens when I am exposed to Ozone?

Breathing ozone can cause:

  • Chest pain
  • Coughing and wheezing
  • Difficulty breathing
  • Irritation of the lungs and throat
  • Congestion

Long-term exposure to ozone can cause:

  • Lung damage and reduced lung function
  • Inflammation of airways
  • Respiratory distress
  • Aggravated lung diseases
  • Increased asthma attacks
  • Increased risk of early death from heart or lung disease

Who is at risk for exposure to Ozone?

Everyone can be exposed to some ozone, especially in the summer. People who are most at risk when exposed to ozone are:

  • People with asthma or other lung diseases
  • People who exercise or work outside
  • Children and older adults

Reduce your risk

If you think your health has been affected by exposure to ozone, contact your health care professional. 

Always wash your hands thoroughly after handling chemicals. For poisoning emergencies or questions about possible poisons, please contact your local poison control center at 1-800-222-1222.

  • Do you exercise or work outdoors during the summer?
  • Be aware of ozone air quality levels, especially in the summer or when outdoor temperatures are high.
  • Avoid exercising or working outdoors when ozone levels are high.
  • If you are elderly, or have asthma or any other respiratory diseases, avoid being outdoors when ozone levels are high.
  • If ozone levels are high, limit your children’s time playing outdoors.
National Library of Medicine Resources and Databases
Additional Resources
  • Ozone Layer Protection

    Information on ozone layer protection, including links to resources addressing ozone depletion, sun safety, and managing refrigerant emissions.

  • Ozone: Good Up High, Bad Nearby

    Resource on ozone addressing its positive and negative effects, and how its depletion impacts human health and the environment.

  • Air Quality Guide for Ozone

    A chart that explains the Air Quality Index for ground-level ozone exposure, and a corresponding factsheet on associated health risks, and how to protect yourself.

  • Ozone

    Information on ozone layer protection, including links to resources addressing ozone depletion, sun safety, and managing refrigerant emissions.

  • Air Trends: Ozone Trends

    Data and interactive charts on national and regional ozone level trends from 1980-2017.

  • The Ozone Hole and Science (United Nations )

    Information on the ozone hole, and ozone depleting substances in different industry sectors.

Back to top