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Secondhand Smoke

What is secondhand smoke?

Secondhand smoke is:

  • the smoke given off by the burning end of a cigarette, pipe, or cigar
  • the smoke exhaled from the lungs of smokers

When nonsmokers breathe this smoke, it is called passive smoking.

Is secondhand smoke dangerous?

Exposure to tobacco smoke is dangerous to everyone. Every time someone smokes, poisonous chemicals are released into the air, such as formaldehyde, cyanide, carbon monoxide, and ammonia. Many of these chemicals are known to cause cancer in humans or animals.

Each year, many nonsmokers die from lung cancer as a result of breathing secondhand smoke. Secondhand smoke can also cause:

  • death from heart disease
  • worsened asthma symptoms and more asthma attacks
  • irritation of the eyes, nose, and throat
  • cancer of the cervix
  • more menstrual pain
  • low birth weight in newborns
  • nausea
  • hoarseness.

Children exposed to secondhand smoke are more likely to get sick. They are more likely to have:

  • asthma
  • frequent upper respiratory infections, such as colds
  • ear infections.

Exposure to cigarette smoke appears to be a factor in SIDS (sudden infant death syndrome). Babies whose mothers smoke, both during pregnancy and after, are more likely to die of SIDS than babies of nonsmoking mothers. Also, research suggests possible links between mothers who smoke and attention-deficit disorder (ADHD) in their children. And there is a greater chance that children of smokers will become smokers.

If you are regularly around someone who smokes at least a few cigarettes a day, your risks of medical problems are similar to the increased risks for smokers. A nonsmoker in a very smoky room for 1 hour with several smokers inhales as many bad chemicals as someone who has smoked 10 or more cigarettes. If you live or work in a smoky environment:

  • You increase your chances of having a heart attack by 50%.
  • Your chances of getting cancer or asthma are doubled.
  • If you get pregnant, the risk of miscarriage or premature delivery is higher.

How close to tobacco smoke do I have to be for it to hurt me?

There is no safe level of tobacco smoke. However, the closer you are to the smoke coming from the end of a cigarette, cigar, or pipe, the worse it is for you. Being in a car with a smoker is especially bad, even if the windows are open. But you can also be exposed to dangerous levels in homes of smokers (even with open windows) and anywhere that allows smoking. Smoke and the chemicals from it linger in dust and on carpet, floors, counters, and other surfaces.

Even if you drink or dine in nonsmoking areas of bars and restaurants, you will still inhale quite a bit of smoke. On average, you will inhale about 50% of the smoke you would inhale in the smoking areas.

What are some of the ways to avoid secondhand smoke?

  • Try to avoid places where people smoke.
  • Don’t smoke in your house or car and don’t let others do so.
  • If smoking is allowed at your workplace, ask your employer to make sure you don’t have to breathe other people's smoke.
  • Make sure your child's day-care, school, and after-school programs are smoke free.
  • In restaurants and bars ask to be seated as far away from smokers as possible.
  • Insist on enforcement of nonsmoking laws.

By promoting smoke-free environments, we are helping to protect everyone's health.

For more information, contact your local chapter of the American Cancer Society or the American Lung Association. You can also visit their Web sites at and

Developed by RelayHealth.
Published by RelayHealth.
Last modified: 2011-06-22
Last reviewed: 2011-04-03
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
© 2011 RelayHealth and/or its affiliates. All rights reserved.
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