Tobacco Smoke Exposure

Secondhand smoke is the smoke you breathe in when someone nearby is smoking. It includes the smoke given off by the burning tobacco. And it includes the smoke breathed out by the smoker.

Thirdhand smoke (THS) is another term you may hear. THS is the smoke that stays on indoor surfaces such as furniture, toys, and carpets. It also stays on clothing, skin, and hair. The American Academy of Pediatrics warns of the possible harmful effects of THS.

How secondhand smoke causes harm

Secondhand smoke contains thousands of chemicals. These include:

  • Nicotine

  • Ammonia

  • Arsenic

  • Benzene

  • Carbon monoxide

  • Formaldehyde

  • Hydrogen cyanide

Many of these are known to be harmful. Some are even known to cause cancer.

Secondhand smoke can cause some problems right away. These include:

  • Coughing

  • Sneezing

  • Shortness of breath

  • Eye irritation

  • Triggering an asthma attack

The chemicals also cause harm right away to your heart and blood vessels. They may raise your blood pressure and lower your good (HDL) cholesterol. The smoke may make your blood clot more easily. This can put you at risk for a blood clot that can lead to a stroke or heart attack.

Long-term health problems

Contact with secondhand smoke raises the risk for some health problems over time. It may also make some health problems happen more often and be more severe. Because of this, secondhand smoke can cause death. Health problems linked to secondhand smoke include:

  • Lung cancer

  • Breast cancer

  • Other cancers. These include leukemia, lymphoma, brain tumors, and cancers of the larynx, bladder, and stomach.

  • Heart disease. This may lead to heart attack.

  • Peripheral artery disease

  • Stroke

  • Ear infections, especially in children

  • Asthma

  • More illness more often, in children

  • Respiratory infections. These include bronchitis and pneumonia.

  • Scarring of the air passages in the lungs

  • SIDS (sudden infant death syndrome)

  • Miscarriage, stillborn birth, or low birth weight

Are you exposed to secondhand smoke?

Millions of people are exposed to secondhand smoke. This includes many young children. Children are more at risk from the health effects of secondhand smoke.

Cigarettes are the main source of secondhand smoke. Pipes, cigars, and other methods of smoking tobacco can also give off secondhand smoke. A single cigar can create as much secondhand smoke as a whole pack of cigarettes.

If you’re in an area where other people are smoking, you’re breathing in secondhand smoke. You may breathe in secondhand smoke in bars, restaurants, and other public places. And you may breathe it in at home, at your workplace, or in a car. You may be at a higher risk for exposure if you live with a smoker. You may also be at higher risk if you work in a place that allows smoking, such as a bar. Luckily more and more states are enacting smoking bans in public places. And more than half of U.S. states have laws banning smoking in enclosed public places.

Secondhand smoke exposure can be measured. This is done by testing indoor air for chemicals found in tobacco smoke, such as nicotine. Your healthcare provider can also test your own exposure level. This is done by measuring the level of cotinine in your blood, saliva, or urine. Cotinine is a chemical created after nicotine enters the body. If you have high levels of cotinine, you likely have high levels of other chemicals from smoke.

But this type of testing is not often needed. If you spend a lot of time in places where people smoke, you likely have high levels of chemicals in your body from the smoke. This is true even if you don’t smoke. If you spend only a small amount of time around smoke, your levels are likely lower.

Preventing contact with secondhand smoke

You can lower your contact with secondhand smoke. Make sure to also protect children and people with health problems from the smoke. You can do this by not going to places where smoking is allowed. If you live with a smoker, ask the person to smoke only outside. Don't allow people to smoke around your children or in your car.

Open windows, use air filters, and put in air ventilation systems. These things may reduce contact with secondhand smoke. But they don't stop contact. Stopping smoking indoors is the only way to protect people from secondhand smoke.

Less is known about the dangers of THS. But consider "no smoking" rules in your home to keep it free of the chemicals in tobacco smoke. Don't stay indoors where people often smoke. If you have long-term smokers in your home, ask them to seek help to stop smoking. Consider replacing carpets, furniture, and window coverings.

For help on quitting smoking, visit

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