Utah Asthma Program
Utah Asthma Program


Ozone is a created by the sun's heat and light acting upon gases and pollution in the atmosphere. Ozone levels change throughout the day and are generally highest in the afternoon hours.


Exposure to high summer ozone levels can cause:

  • Irritation to the eyes, nose and throat
  • Coughing
  • Wheezing
  • Chest tightness
  • Difficulty breathing

Recommendations for Outdoor Physical Activity During Ozone Season (May-September)

The Utah Departments of Health and Environmental Quality have developed recommendations for outdoor physical activity in the summertime to avoid unhealthy exposure to summertime ozone.

  • The best time for outdoor summer physical activity is before noon or after 6:00 pm.
  • If you are physically active between noon and 6:00 pm:
    • Consider light to moderate activity (i.e., walking instead of running),
    • Consider indoor activities.
  • Discuss physical activities with your doctor, especially if you have a lung disease or heart condition.

Additional Resources

  • The Environmental Protection Agency's recommendations for outdoor activity based on ozone level are available here.
  • Symptom Tracking Sheet - A sheet to assist in tracking ozone levels and your symptoms to plan physical activity.

Click here for the average number of high ozone level days throughout the state of Utah.

Click here for the average number of high ozone level days along the Wasatch Front.

Source: Utah Environmental Public Health Tracking Network