Secondhand Smoke

Introduction
What chemicals are present in secondhand smoke?
What are the health effects of exposure to secondhand smoke?
What is being done to reduce nonsmokers’ exposure to secondhand smoke?
Babies are hurt by secondhand smoke
Secondhand smoke hurts adults

Secondhand smoke, also called environmental tobacco smoke (ETS), is the combination of two forms of smoke from burning tobacco products: sidestream smoke and mainstream smoke. Sidestream smoke, which makes up about half of all secondhand smoke, comes from the burning end of a cigarette, cigar, or pipe. Mainstream smoke is exhaled by the smoker. Exposure to secondhand smoke is also called involuntary smoking or passive smoking.

Many factors affect what chemicals are present in secondhand smoke. These factors include the type of tobacco, the chemicals added to the tobacco, how the product is smoked, and the paper in which the tobacco is wrapped. More than 4,000 chemicals have been identified in mainstream tobacco smoke; however, the actual number may be more than 100,000.

Of the chemicals identified in secondhand smoke, more than 50 are carcinogens (substances that cause cancer), such as formaldehyde. Six other substances, including nicotine and carbon monoxide, interfere with normal cell development. Some of the compounds present in secondhand smoke become carcinogenic only after they are activated by specific enzymes (proteins that control chemical reactions) in the body. After these compounds are activated, they can then become part of a cell’s DNA and may interfere with the normal growth of cells.

Secondhand smoke exposure is a known risk factor for lung cancer. Approximately 3,000 lung cancer deaths occur each year among adult nonsmokers in the United States as a result of exposure to secondhand smoke. Secondhand smoke is also linked to nasal sinus cancer. Some research suggests an association between secondhand smoke and cancers of the cervix, breast, and bladder. However, more research is needed in order to confirm a link to these cancers.

Secondhand smoke is also associated with the following noncancerous conditions:

• Chronic coughing, phlegm, and wheezing.
• Chest discomfort.
• Lowered lung function.
• Severe lower respiratory tract infections, such as bronchitis or pneumonia, in children.
• More severe asthma and increased chance of developing asthma in children.
• Eye and nose irritation.
• Severe and chronic heart disease.
• Middle ear infections in children.
• Sudden infant death syndrome (SIDS).
• Low birthweight or small size at birth for babies of women exposed to secondhand smoke during pregnancy.

Certain other noncancerous health conditions may also be associated with secondhand smoke. However, more research is needed in order to confirm a link between these conditions and secondhand smoke. These conditions include:

• Spontaneous abortion (miscarriage).
• Adverse effect on cognition and behavior in children.
• Worsening of cystic fibrosis (a disease that causes excessive mucus in the lungs).

Studies have shown that even small amounts of secondhand smoke exposure can be harmful to people’s health. The only way to fully protect nonsmokers from secondhand smoke exposure is to eliminate smoking in indoor spaces. Separating smokers from nonsmokers, cleaning the air, and ventilating buildings cannot completely eliminate secondhand smoke exposure. Individuals can reduce their exposure to secondhand smoke by not allowing smoking in their home or car. Educational, clinical, and policy interventions have also been shown to reduce secondhand smoke exposure. Such policies include adoption of worksite restrictions, passage of clean indoor air laws, and enforcement of smoking restrictions in shared environments.

Many states and local governments have passed laws prohibiting smoking in public facilities such as schools, hospitals, airports, and bus terminals. Some states also require private employers to create policies that protect employees who do not smoke, and several local communities have enacted nonsmokers’ rights laws, most of which are stricter than state laws.

Tobacco smoke harms babies before and after they are born. Unborn babies are hurt when their mothers smoke or if others smoke around their mothers. Babies also may breathe secondhand smoke after they are born. Because their bodies are developing, poisons in smoke hurt babies even more than adults. Babies under a year old are in the most danger. Secondhand smoke is a known cause of sudden infant death syndrome (SIDS). The sudden, unexplained, unexpected death of an infant before age 1 year is known as SIDS. The exact way these deaths happen is still not known. We suspect it may be caused by changes in the brain or lungs that affect how a baby breathes. During pregnancy, many of the compounds in secondhand smoke change the way a baby’s brain develops. Mothers who smoke while pregnant are more likely to have their babies die of SIDS. Babies who are around secondhand smoke-from their mother, their father, or anyone else-after they are born, are also more likely to die of SIDS than children who are not around secondhand smoke.

Secondhand smoke causes low birth weight and lung problems in infants. Babies whose mothers are around secondhand smoke are more likely to have lower birth weights. These babies can have more health problems because they breathe smoke. For example, they are more likely to have infections than babies who are not around secondhand smoke. Studies show that babies whose mothers smoke while pregnant are more likely to have lungs that do not develop in a normal way. Babies who breathe secondhand smoke after birth also have weaker lungs. These problems can continue as they grow older and even when they become adults.

The longer you are around secondhand smoke, the more likely it is to hurt you. Nonsmokers who breathe smoke at home or at work are more likely to become sick and die from heart disease and lung cancer. Studies show that secondhand smoke may cause other serious diseases, too.

Secondhand smoke is bad for your heart. Breathing secondhand smoke makes the platelets in your blood behave like those of a regular smoker. Even a short time in a smoky room causes your blood platelets to stick together. Secondhand smoke also damages the lining of your blood vessels. In your heart, these bad changes can cause a deadly heart attack.

Secondhand smoke changes how your heart, blood, and blood vessels work in many ways. Adults who breathe 5 hours of secondhand smoke daily have higher “bad” cholesterol that clogs arteries.

Secondhand smoke includes many chemicals that are dangerous for your lungs. Secondhand smoke is especially dangerous for young children and adults with heart and lung disease. Secondhand smoke causes lung cancer in adults who don’t smoke. Breathing in secondhand smoke at home or work increases your chances of getting lung cancer by 20 percent to 30 percent.