Secondhand Smoke (Environmental Tobacco Smoke)

Secondhand smoke is the smoke you’re exposed to when someone nearby is smoking. It includes the smoke breathed out by the smoker. And it includes the smoke given off by the burning tobacco.

How secondhand smoke causes harm

Secondhand smoke contains thousands of chemicals, including:

  • Nicotine

  • Ammonia

  • Arsenic

  • Benzene

  • Carbon monoxide

  • Formaldehyde

  • Hydrogen cyanide

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

Secondhand smoke can cause some problems right away, such as:

  • Coughing

  • Sneezing

  • Shortness of breath

  • Eye irritation

The chemicals also cause instant harm to your heart and blood vessels. They may increase your blood pressure and lower your good (HDL) cholesterol. The smoke may increase the clotting of your blood. This can put you at risk for a blood clot that can lead to a stroke or heart attack.

Long-term health problems from secondhand smoke

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, including leukemia, lymphoma, brain tumors, and cancers of the larynx, bladder, and stomach

  • Heart disease, which may lead to heart attack

  • Peripheral artery disease

  • Stroke

  • Ear infections, especially in children

  • Asthma

  • Respiratory infections, such as bronchitis and pneumonia

  • Scarring of the air passages in the lungs

  • Sudden infant death syndrome (SIDS)

  • 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 being exposed to secondhand smoke. You may breathe in secondhand smoke in bars, restaurants, or 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 secondhand smoke 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.

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 level of exposure. 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 exposure to 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 avoiding places where smoking is allowed. If you live with a smoker, ask the person to smoke only outside.

Open windows, use air filters, and install air ventilation systems. These may lessen contact with secondhand smoke. But they do not stop contact. Prevent smoking indoors is the only way to protect people from secondhand smoke.