Smog, Ozone and How They Affect Your Lungs

Smog, Ozone and How They Affect Your Lungs

Breathing in heavy smog for just one hour can harm your lungs, especially if you are elderly. The danger is worst on hot, sunny days.

Air pollution is bad for the environment. But for some people, smog can be life-threatening.

Smog contains ozone, a colorless gas that is harmful to breathe at high levels. Just one to three hours in heavy smog can impair lung function. Hospital admissions rise as well when ozone levels are high, especially for those with chronic lung disease. One major study linked rising ozone levels to a marked increase in deaths over a 14-year period.

The danger is worst on hot, sunny days when ozone concentrations are highest. The elderly are most vulnerable.

Heat alert

Not all ozone is bad. The ozone layer in the upper atmosphere shields the earth from much of the sun’s harmful ultraviolet rays. It’s the ozone produced at ground level that can irritate lungs and airways.

Ground-level ozone is formed when fossil fuels emitted by cars, power plants and other sources react with sunlight and heat. “Bad ozone” can also form when certain chemicals, like paints, evaporate.

High levels of ozone can cause:

  • Shortness of breath
  • Chest discomfort
  • Pain when breathing deeply
  • Wheezing and coughing
  • Asthma attacks
  • Headaches
  • Rapid or shallow breathing

CALL 9-1-1 if you’re outside on a hot day and feel chest discomfort or pain, or if you are having a hard time breathing.

For some, the symptoms are painful and can last for a few hours. People with chronic lung disease (such as emphysema, bronchitis or asthma) or heart failure often find that their conditions get worse. Ozone can also reduce the ability to fight off infections in the lungs. Over time, ozone exposure can speed up the natural decline of lung function that occurs with age, too.

Seniors at highest risk

New research shows that people over age 65 have twice the chance of dying from ozone exposure than other groups. This is partly due to age-related factors. These include shrinking respiratory muscles, compromised immune systems and loss of lung wall surface and muscle fibers. The same study showed that deaths from ozone also occur more in people with atrial fibrillation, African Americans and women.

Other groups that are more sensitive to harm from ozone are:

  • Children and teens, especially when active
  • People with lung disease
  • People who work outside
  • Those who exercise strenuously outdoors

Avoid ozone exposure

Even if you are not in a high-risk group, try to avoid being outdoors when ozone levels are high. In most parts of the country, summer is the most dangerous time. This is due to the mix of higher temperatures, more sunlight and stagnant air masses.

Seniors and people with lung and certain heart conditions need to be extra careful. Local weather reports often note when ozone levels are high. The U.S. Environmental Protection Agency maintains an Air Quality Index to alert people of daily risks, too. To check current ozone levels where you live, go online to and select your state.

Short of staying inside, plan any outdoor activities before 11 a.m. or after 8 p.m. when ozone levels tend to be lower. Your chances of being affected rise the longer you are outdoors and the more strenuous your activity. Breathing faster lets ozone penetrate deeper into the lungs, where injury is more likely.

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