Questions About Smoking, Tobacco, and Health

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Is secondhand (environmental) tobacco smoke dangerous?

There’s no safe level of exposure for secondhand smoke (SHS), which is also called environmental tobacco smoke. Passive smoking (inhaling secondhand smoke) happens when non-smokers breathe other people’s tobacco smoke. This includes mainstream smoke (smoke that’s exhaled into the air by smokers) and sidestream smoke (smoke that comes directly from the burning tobacco).

SHS contains the same harmful chemicals the smokers inhale. It’s known to cause lung cancer in non-smokers, and has been linked to other cancers and health problems in non-smokers, too. Children and babies are at special risk: those who breathe secondhand smoke are more likely to get sick and even die than children who aren’t around SHS.

Please see our document called Secondhand Smoke to learn more.

Am I at risk for lung cancer from smoke odors on clothing or from being in a room that still smells like tobacco smoke?

There are no medical research reports on the cancer-causing effects of cigarette odors, but research does show that secondhand smoke (SHS) can seep into hair, clothing, dust, and other surfaces. Researchers call this “thirdhand” smoke. It refers to particles that are left on surfaces after you can no longer see the smoke. These particles can become airborne again when disturbed, or they can be picked up by people (especially babies and small children) who touch the surfaces and get particles on their hands and bodies.

Polycyclic aromatic hydrocarbons (PAHs) are known carcinogens that have been found in settled house dust in the homes of smokers. Studies in mice and in the lab have suggested that these substances still have effects and may cause harm if ingested, but human studies have not been done. Though the cancer-causing effects of thirdhand smoke is not known, this is an active area of tobacco research.

For more information, see our document called Secondhand Smoke.


Last Medical Review: 02/13/2014
Last Revised: 02/13/2014