Secondhand Smoke

What is secondhand smoke?

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.

In the U.S., cigarettes are the main source of secondhand smoke. Pipes, cigars, and other ways 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.

Tobacco smoke is a mixture of gases and particles. It is filled with many chemicals that can harm your health. Being exposed to the smoke increases your risk of lung diseases, some types of cancer, and other health problems. Even contact with a small amount of smoke can cause problems.

Millions of people in the U.S. are exposed to secondhand smoke each year. This includes many young children. Children are more at risk for the effects of secondhand smoke.

In recent years, contact with secondhand smoke has lessened. This is because smoking has been banned in many public places. Also, fewer people smoke. And more homes have smoke-free rules.

What effects does secondhand smoke have on health?

No level of secondhand smoke is safe. Even a small amount of contact can cause problems.

Secondhand smoke has thousands of chemicals. Many of these are known to be harmful, including:

  • Nicotine
  • Ammonia
  • Arsenic
  • Benzene
  • Beryllium
  • Carbon monoxide
  • Formaldehyde
  • Hydrogen cyanide
  • Toluene

The chemicals found in secondhand smoke depend on: 

  • The type and amount of tobacco
  • The chemicals added to it
  • The way it’s smoked

The chemicals have been found in the blood of nonsmokers who have been in contact with secondhand smoke. Many of these chemicals are known to cause cancer. Secondhand smoke is called a cancer-causing agent by several U.S. agencies. 

These chemicals irritate your airways as soon as you’re in contact with secondhand smoke. The chemicals also have instant harmful effects on your heart and blood vessels. They may increase your blood pressure and lower your HDL (good) cholesterol. The smoke may increase the clotting of your blood. This can make it more likely for you to form a blood clot that can lead to a stroke or heart attack.

Who is at risk for secondhand smoke?

You may be at a higher risk 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.

What are the symptoms of secondhand smoke exposure?

The smoke can cause a number of symptoms right away, such as:

  • Coughing
  • Sneezing
  • Feeling short of breath
  • Eye irritation

Many people in contact with secondhand smoke may not have any symptoms right away. But that does not mean the smoke has not caused harm. It can still lead to problems over time. These include chronic bronchitis and scarring of the air passages in the lungs.

How is secondhand smoke exposure measured?

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 testing the level of cotinine in your blood, saliva, or urine. Cotinine is a chemical that is created after nicotine enters the body. If you have high levels of cotinine, you likely have high levels of other chemicals from contact with 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 do not smoke. If you spend only a small amount of time around smoke, your levels are likely lower.

What are possible complications of secondhand smoke?

Contact with secondhand smoke greatly raises the risk of some health problems. It may also make some health problems happen more often, and be more severe. Because of this, the smoke causes thousands of deaths. Health problems linked to secondhand smoke include:

  • Lung cancer
  • Breast cancer
  • Other cancers such as leukemia, lymphoma, brain tumors, and cancers of the larynx, bladder, stomach, and more
  • Heart disease, which may lead to heart attack
  • Peripheral artery disease (PAD)
  • Stroke
  • Ear infections, especially in children
  • Asthma, especially in children
  • Irreversible lung disease such as chronic obstructive pulmonary disease (COPD)
  • Respiratory infections, such as bronchitis and pneumonia
  • Sudden infant death syndrome (SIDS)
  • Miscarriage, stillborn birth, or babies with low birth weights

What can I do to prevent contact with secondhand smoke?

It’s important to protect all people from secondhand smoke. It’s most important to protect children and people with health problems. You can do this by avoiding places where smoking is allowed. If you live with a smoker, ask that he or she smokes only outside. Don't let anyone smoke in your car.

Open windows, air filters, and air ventilation systems may lessen contact with secondhand smoke. But they don’t stop contact. Preventing smoking indoors is the only way to protect people from secondhand smoke.

Many towns and cities have taken steps to reduce secondhand smoke. Many cities now ban smoking in public places. These bans include places such as restaurants, bars, hospitals, airports, and schools. Many states have banned smoking in the workplace. Many advocacy groups argue for more smoking bans to protect people from secondhand smoke.

Key points about secondhand smoke

  • Secondhand smoke is the smoke you breathe in when someone nearby is smoking. You breathe in the chemicals in tobacco smoke, even if you don’t smoke.
  • The smoke causes instant harm to the lungs, heart, and blood vessels.
  • The smoke can lead to many health problems. These include cancer, heart disease, stroke, lung infections, and asthma.
  • No level of contact with secondhand smoke is safe. Your risk of health problems may increase with the amount of smoke you are exposed to.
  • Millions of people in the U.S. are exposed to secondhand smoke each year.

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