Spending Time Outdoors? Pay Attention to Ozone Levels

Janet Tiberian Author
By Janet Tiberian, MA, MPH, CHES
August 18, 2023
NYC Sunset with Smog

It’s still summer, which means most people are spending time outdoors enjoying the warm weather and sunshine. You’ll be happy to know that sun exposure helps boost vitamin D levels, raise serotonin levels, reduce the risk for autoimmune diseases, regulate genetics, decrease skin conditions and prevent nerve dysfunction.

But summer weather has risks: sunburn, heat stroke, heat exhaustion, dehydration, sunburn and sun damage. We also have to deal with higher ozone levels. Generally, ozone levels are higher on hot, sunny summer days, particularly when the air is stagnant.


Ozone, an odorless, colorless gas comprised of three oxygen molecules, is a natural part of the environment. Ninety percent of ozone resides in the Earth's upper atmosphere where it forms the ozone layer – a protective barrier that shields the Earth’s surface from ultraviolet-B (UV-B) radiation emitted from the sun. UV-B radiation harms plants and is the type of radiation linked to sunburns, skin damage, melanoma, cataracts, diminished vision and immune suppression.

The remaining 10 percent of ozone is in the lower atmosphere. Ground-level ozone is produced when sunlight triggers an interaction between volatile organic compounds (VOCs) and nitrogen oxides, forming the primary pollutant in smog. It’s also one of the pollutants released into the environment through cars and trucks, industrial facilities, refineries, power plants, household products and cleaning supplies, paints and solvents and wildfires. During the summer, ozone is more intense because hot temperatures and sunlight increase the reaction among the compounds, generating more of it.  

Ozone and Your Health

Besides lowering air quality and damaging crops, forests and plants, ozone can irritate and inflame the throat, lung lining and respiratory tract causing:

  • Sore throat
  • Congestion
  • Coughing
  • Chest tightness, wheezing, shortness of breath
  • Reduce lung function.
  • Respiratory infections
  • Exacerbated asthma, bronchitis and emphysema.
  • Permanent scar lung tissue (regular exposure)

Ozone can affect anyone. But some people are more susceptible to ozone-related health issues such as young children, pregnant women, older adults, people who spend a lot of time outdoors and those with high blood pressure, heart disease and pulmonary conditions.

Limiting Ozone Exposure

Lower your risk of ozone complications by following these recommendations from National Jewish Health:

  • Watch your local weather forecasts for high pollution days and staying indoors when possible. On days like these, make sure you exercise at home or at the gym.   
  • Plan most of your outdoor activities in the morning, as ozone levels are higher in the afternoon and early evening.
  • Choose exercises that require less exertion if you decide to workout outdoors.
  • Use a high efficiency particulate air absorbing (HEPA) filter in air conditioners and vacuums to trap pollutants.
  • Set your thermostat climate control on circulate mode to limit the number of polluted air molecules entering into your home.

For more information on ozone, please visit the U.S. Environmental Protection Agency »

About the Author
Janet Tiberian Author
Janet Tiberian, MA, MPH, CHES

Janet Tiberian is MDVIP's health educator. She has more than 25 years experience in chronic disease prevention and therapeutic exercise.

View All Posts By Janet Tiberian, MA, MPH, CHES
Physician Locator
Enter a full address, city, state, or ZIP code. You can also browse our city directory to find physicians in your area.
Enter Doctor's Name