An official website of the United States government.

Ground-level Ozone Pollution

The ozone molecule (O3) is harmful to air quality outside of the ozone layer. EPA regulations help states reduce ozone levels in outdoor air.

Ground-level Ozone Pollution

Ozone can be “good” or “bad” for health and the environment depending on where it’s found in the atmosphere. Stratospheric ozone is “good” because it protects living things from ultraviolet radiation from the sun. Ground-level ozone, the topic of this website, is “bad” because it can trigger a variety of health problems, particularly for children, the elderly, and people of all ages who have lung diseases such as asthma. Learn more about ground-level ozone.

Air Quality Where You Live

  • View current and forecasted air quality conditions across the U.S.
  • Explore current locations of wildfires
  • Review data from air quality monitors across the world


Note: AirNow is experiencing extremely heavy traffic and may be slow. Visit an alternate map showing air quality from fires.