Secondhand smoke: Avoid dangers in the air

Exposure to the toxins in secondhand smoke can cause serious health problems. Know what you're breathing — and consider practical steps to protect your family.

By Mayo Clinic Staff

You don't smoke because you understand the dangers — but what about smoke you inhale involuntarily? Secondhand smoke causes and contributes to various health problems, including heart disease and lung cancer. And with adult smokers numbering about 1 billion worldwide, secondhand smoke exposure is virtually unavoidable for children and adults who don't smoke.

Understand what's in secondhand smoke, and consider ways to protect yourself and those you love from it.

What's in secondhand smoke?

Secondhand smoke includes the smoke that a smoker exhales (mainstream smoke) and the smoke that comes directly from the burning tobacco product (sidestream smoke).

Secondhand smoke contains toxic chemicals, including:

  • Ammonia, used in cleaning products
  • Benzene, found in gasoline
  • Cadmium, a toxic metal
  • Cyanide, used in chemical weapons
  • Formaldehyde, an industrial chemical

It isn't just the smoke that's a concern, though. The residue that clings to household dust and surfaces is called thirdhand smoke. Young children are particularly at risk for thirdhand smoke exposure due to their frequent contact with contaminated materials, such as carpeting.

How risky is secondhand smoke?

Secondhand smoke causes or contributes to serious health problems, including:

  • Cancer. Secondhand smoke is a known risk factor for lung cancer.
  • Heart disease. Exposure to secondhand smoke increases the risk of heart disease by about 25% to 30%.
  • Chronic lung disease. Exposure to secondhand smoke even for a short time causes measurable decreases in lung function. This can lead to chronic lung disease.

Secondhand smoke poses additional risks for children, who are especially vulnerable to the effects of secondhand smoke. Problems include:

  • Reduced birth weight. Exposure to secondhand smoke during pregnancy increases the risk of having a baby with a reduced birth weight.
  • Sudden infant death syndrome (SIDS). Secondhand smoke exposure is believed to increase the risk of SIDS.
  • Asthma and respiratory illness. Secondhand smoke exposure is linked with the increased risk — and severity — of childhood asthma and wheezing. Infants of parents who smoke are more likely to develop bronchitis and pneumonia during the first year of life.

How can secondhand smoke be avoided?

With planning, you can reduce your family's exposure to secondhand smoke. Start with these simple steps:

  • Don't allow smoking in your home. Opening windows and using fans and ventilation systems doesn't eliminate exposure to secondhand smoke.
  • Don't allow smoking in your vehicle, even with the windows down. If a passenger must smoke while you're traveling, stop as needed for smoke breaks outside the car.
  • Choose smoke-free care facilities. This applies to child care facilities as well as facilities for older adults.
  • Patronize businesses with no-smoking policies. Choose smoke-free restaurants. When you travel, request nonsmoking hotel rooms and rental cars.

If you have a partner or other loved one who smokes, offer support and encouragement to stop smoking. The entire family will benefit.

March 20, 2020 See more In-depth

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