Health Effects of Secondhand Smoke

Secondhand smoke is the combination of smoke from the burning end of a cigarette and the smoke breathed out by smokers. Secondhand smoke contains more than 7,000 chemicals. Hundreds are toxic and about 70 can cause cancer.^1,2,3,4

Since the 1964 Surgeon General’s Report, 2.5 million adults who were nonsmokers died because they breathed secondhand smoke.¹

There is no risk-free level of exposure to secondhand smoke.

• Secondhand smoke causes numerous health problems in infants and children, including more frequent and severe asthma attacks, respiratory infections, ear infections, and sudden infant death syndrome (SIDS).^1,4
• Smoking during pregnancy results in more than 1,000 infant deaths annually.⁴
• Some of the health conditions caused by secondhand smoke in adults include coronary heart disease, stroke, and lung cancer.^1,4

Health Consequences Causally Linked to Exposure to Secondhand Smoke

Note:
The condition in red is a new disease causally linked to secondhand smoke in the 2014 Surgeon General’s Report⁴

Secondhand Smoke Causes Cardiovascular Disease

Exposure to secondhand smoke has immediate adverse effects on the cardiovascular system and can cause coronary heart disease and stroke.^2,4,5

• Secondhand smoke causes nearly 34,000 premature deaths from heart disease each year in the United States among nonsmokers.⁴
• Nonsmokers who are exposed to secondhand smoke at home or at work increase their risk of developing heart disease by 25–30%.¹
• Secondhand smoke increases the risk for stroke by 20−30%.⁴
• Secondhand smoke exposure causes more than 8,000 deaths from stroke annually.⁴

Breathing secondhand smoke can have immediate adverse effects on your blood and blood vessels, increasing the risk of having a heart attack.^2,3,4

• Breathing secondhand smoke interferes with the normal functioning of the heart, blood, and vascular systems in ways that increase the risk of having a heart attack.
• Even brief exposure to secondhand smoke can damage the lining of blood vessels and cause your blood platelets to become stickier. These changes can cause a deadly heart attack.

People who already have heart disease are at especially high risk of suffering adverse effects from breathing secondhand smoke and should take special precautions to avoid even brief exposures.¹

Secondhand Smoke Causes Lung Cancer

Secondhand smoke causes lung cancer in adults who have never smoked.⁴

• Nonsmokers who are exposed to secondhand smoke at home or at work increase their risk of developing lung cancer by 20–30%.²
• Secondhand smoke causes more than 7,300 lung cancer deaths among U.S. nonsmokers each year.⁴
• Nonsmokers who are exposed to secondhand smoke are inhaling many of the same cancer-causing substances and poisons as smokers.^2,3,4
• Even brief secondhand smoke exposure can damage cells in ways that set the cancer process in motion.⁴
• As with active smoking, the longer the duration and the higher the level of exposure to secondhand smoke, the greater the risk of developing lung cancer.⁴

Secondhand Smoke Causes SIDS

Sudden Infant Death Syndrome (SIDS) is the sudden, unexplained, unexpected death of an infant in the first year of life. SIDS is the leading cause of death in otherwise healthy infants.⁶ Secondhand smoke increases the risk for SIDS.^2,4

• Smoking by women during pregnancy increases the risk for SIDS.^2,4,7
• Infants who are exposed to secondhand smoke after birth are also at greater risk for SIDS.^2,4
• Chemicals in secondhand smoke appear to affect the brain in ways that interfere with its regulation of infants' breathing.^2,4
• Infants who die from SIDS have higher concentrations of nicotine in their lungs and higher levels of cotinine (a biological marker for secondhand smoke exposure) than infants who die from other causes.^2,4

Parents can help protect their babies from SIDS by taking the following three actions:⁸

• Do not smoke when pregnant.
• Do not smoke in the home or around the baby.
• Put the baby down to sleep on its back.

Secondhand Smoke Harms Children

Secondhand smoke can cause serious health problems in children.^2,4

• Studies show that older children whose parents smoke get sick more often. Their lungs grow less than children who do not breathe secondhand smoke, and they get more bronchitis and pneumonia.
• Wheezing and coughing are more common in children who breathe secondhand smoke.
• Secondhand smoke can trigger an asthma attack in a child. Children with asthma who are around secondhand smoke have more severe and frequent asthma attacks. A severe asthma attack can put a child's life in danger.
• Children whose parents smoke around them get more ear infections. They also have fluid in their ears more often and have more operations to put in ear tubes for drainage.

Parents can help protect their children from secondhand smoke by taking the following actions:⁹

• Do not allow anyone to smoke anywhere in or near your home.
• Do not allow anyone to smoke in your car, even with the window down.
• Make sure your children’s day care centers and schools are tobacco-free.
• If your state still allows smoking in public areas, look for restaurants and other places that do not allow smoking. “No-smoking sections” do not protect you and your family from secondhand smoke.

References

1. U.S. Department of Health and Human Services. Let’s Make the Next Generation Tobacco-Free: Your Guide to the 50th Anniversary Surgeon General’s Report on Smoking and Health. [PDF–795 KB] Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2014 [accessed 2016 Jan 11].
2. U.S. Department of Health and Human Services. The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2006 [accessed 2017 Jan 11].
3. U.S. Department of Health and Human Services. A Report of the Surgeon General: How Tobacco Smoke Causes Disease: What It Means to You. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2010 [accessed 2017 Jan 11].
4. U.S. Department of Health and Human Services. The Health Consequences of Smoking—50 Years of Progress: A Report of the Surgeon General. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2014 [accessed 2017 Jan 11].
5. Institute of Medicine. Secondhand Smoke Exposure and Cardiovascular Effects: Making Sense of the Evidence. Washington: National Academy of Sciences, Institute of Medicine, 2010 [accessed 2017 Jan 11].
6. American Academy of Pediatrics, Task Force on Sudden Infant Death Syndrome. The Changing Concept of Sudden Infant Death Syndrome: Diagnostic Coding Shifts; Controversies Regarding the Sleeping Environment; and New Variables to Consider in Reducing Risk. Pediatrics 2005;116(5):1245–55 [cited 2017 Jan 11].
7. U.S. Department of Health and Human Services. The Health Consequences of Smoking: A Report of the Surgeon General. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2004 [accessed 2017 Jan 11].
8. Centers for Disease Control and Prevention. CDC Features: Sudden Infant Death Syndrome (SIDS) [last updated 2013 Oct 25; accessed 2017 Jan 11].
9. U.S. Department of Health and Human Services. How Tobacco Smoke Causes Disease: What It Means to You. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2010 [accessed 2017 Jan 11].