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The Dangers of Secondhand & Thirdhand Smoke Exposure

Several types of tobacco products produce a smoke or aerosol that is harmful to both the user and other people nearby who are not using these products.

What exactly is secondhand and thirdhand smoke exposure, and how can they affect you? View our infographicPDF icon and printable handoutPDF icon explaining thirdhand smoke, and then open the tabs below to learn more and find out what you can do to protect your health and the health of others.

  • Secondhand smoke and the harmful chemicals in it are known causes of Sudden Infant Death Syndrome, RESPIRATORY INFECTIONS, ear infections, and asthma attacks in infants and children. They are also known causes of HEART DISEASE, stroke, and lung cancer in adult nonsmokers.

    Secondhand smoke is in the air around smokers. It is a mixture of the smoke from the burning end of the cigarette (or other smoked tobacco product) and the smoke breathed out by smokers.

    There is no "risk-free" or "safe" level of secondhand smoke exposure; even brief exposure to secondhand smoke can be harmful to health. In fact, according to the Centers for Disease Control and Prevention (CDC), secondhand smoke exposure contributes to approximately 41,000 deaths among non-smoking adults and 400 deaths in infants each year. (Source: Smoking and Tobacco Use - Basic Information: Secondhand Smoke)

    E-cigarettes also produce similar harmful emissions in the form of the e-cigarette aerosol that people exhale when using e-cigarettes. This secondhand aerosol can harm people nearby who are not using these products. (For more information about e-cigarettes, please visit our special e-cigarettes page on this website.)

    Findings about the dangers of secondhand smoke have been supported by many scientific studies and reports, including the 2006 U.S. Surgeon General's Report: The Health Consequences of Involuntary Exposure to Tobacco Smoke.

    The six major conclusions of the 2006 report are:

    • Many millions of Americans, both children and adults, are still exposed to secondhand smoke in their homes and workplaces, despite substantial progress in tobacco control.
    • Secondhand smoke causes premature death and disease in children and in adults who do not smoke.
    • Children exposed to secondhand smoke are at an increased risk for sudden infant death syndrome (SIDS), acute respiratory infections, ear problems, and more severe asthma. Smoking by parents causes respiratory symptoms and slows lung growth in their children.
    • Exposure to secondhand smoke as an adult causes immediate adverse effects on the cardiovascular system and can result in coronary heart disease and lung cancer.
    • Scientific evidence indicates that there is no risk-free level of exposure to secondhand smoke.
    • Eliminating smoking in indoor spaces is the only way to fully protect nonsmokers from exposure to secondhand smoke. Separating smokers from nonsmokers, cleaning the air, and ventilating buildings cannot fully eliminate nonsmokers' exposure to secondhand smoke.
  • Thirdhand smoke is what sticks on surfaces, such as walls, ceilings, furniture, car seats, clothing, dust, and even hair, long after someone has smoked a cigarette in the area. It is important to remember there is no safe level of exposure to tobacco smoke.

    You should know:

    • Smoking in different rooms using fans, or smoking in front of an open window, does not prevent thirdhand smoke.
    • Thirdhand smoke exposure is of special concern when infants and children are being held, are crawling, or are playing, due to the risk of them touching contaminated surfaces and then putting their hands in their mouths or touching their eyes.
    • Disinfecting a home or a car used by a smoker may require expensive professional cleaning, because the smoke residue can stain walls, floors, and other surfaces. The smell of smoke also can remain in drywall, insulation, and other building materials.


  • When someone smokes in a car or vehicle, people breathe dangerous air.

    Exposing passengers to secondhand smoke in a vehicle, even if the windows are down, is extremely dangerous. Being around smoke is harmful to anyone's health, particularly children.

    Because of the small space, smoking in vehicles quickly creates higher levels of secondhand smoke than being in a larger space. Smoking with the vehicle windows closed makes a poisonous gas called carbon monoxide. It is best not to smoke in vehicles.


  • You're in Charge

    You can protect yourself and your family from secondhand and thirdhand smoke and e-cigarette aerosol:

    • If you smoke or use e-cigarettes, quit.
    • Do not allow anyone to smoke or vape anywhere in or near your home.
    • Do not allow anyone to smoke or vape in your car, even with the windows down.
    • Seek out public places that do not allow smoking or the use of e-cigarettes.
    • Teach your children to stay away from secondhand smoke and e-cigarette aerosol.