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 Secondhand smoke exposure occurs when people who do not smoke breathe in smoke exhaled by people who smoke or from burning tobacco products.

Since the 1964 Surgeon General’s Report, 2.5 million adults who do not smoke have died from health problems caused by secondhand smoke exposure.5 There is no safe level of exposure to secondhand smoke; even brief exposure can be harmful to both adults and children.1, 2,6

Everyone deserves a fair and just opportunity to breathe smokefree air and be as healthy as possible. Exposure to secondhand smoke has declined in the U.S., but progress has not been the same for everyone. Secondhand smoke exposure is more common among children ages 3 to 11 years, non-Hispanic Black Americans, people living below the poverty level, and people who rent housing.3 There is still work to do to ensure we achieve smokefree air for all.

Comprehensive smokefree policies and laws in all workplaces and public places – without exception – and adoption of smokefree rules for homes and vehicles are the only way to fully protect people from secondhand smoke exposure,.1,2,7  Comprehensive smokefree laws and policies can also help people who smoke quit and can help keep young people from starting to smoke.3,4,8

Health Consequences Causally Linked to Exposure to Secondhand Smoke

Diagram showing the effects of secondhand smoke. In children: Middle ear disease, respiratory symptoms, impaired lung function, Lower respiratory illness, sudden infant death syndrome.  In Adults:  Stroke, nasal irritation, lung cancer, coronary heart disease, reproductive effects in women; low birth weight

Secondhand Smoke Causes Heart Disease

For adults who do not smoke, exposure to secondhand smoke has immediate harmful effects on the heart and blood vessels and can cause coronary heart disease and stroke.1,3,6

  • Secondhand smoke causes nearly 34,000 premature deaths from heart disease each year in the United States among adults who do not smoke.1
  • People who do not smoke but are exposed to secondhand smoke at home or at work increase their risk of developing heart disease by 25–30%.5
  • Secondhand smoke increases the risk for stroke by 20−30%.1
  • Secondhand smoke causes more than 8,000 deaths from stroke each year.1

For adults who do not smoke, exposure to secondhand smoke has immediate harmful effects on blood and blood vessels and can increase the risk of heart attack.1,2,3

  • Exposure to 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 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 the harmful effects from breathing secondhand smoke and should take special precautions to avoid even brief exposures.1

Secondhand Smoke Causes Lung Cancer

x-ray of lungs with cancer

For adults who never smoked, exposure to secondhand smoke can cause lung cancer.1

  • People who do not smoke but are exposed to secondhand smoke at home or at work increase their risk of developing lung cancer by 20–30%.3
  • Secondhand smoke causes more than 7,300 lung cancer deaths each year among U.S. adults who do not smoke.1
  • People who do not smoke but are exposed to secondhand smoke are inhaling many of the same cancer-causing substances and poisons that are inhaled by people who smoke.1,2,3
  • Even brief exposure to secondhand smoke can damage the body’s cells in ways that set the cancer process in motion.1
  • 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.1

Secondhand Smoke Causes Health Problems in Infants

Secondhand smoke can cause serious health problems in infants.1,

  • Smoking during pregnancy results in more than 1,000 infant deaths annually.1
  • Women exposed to secondhand smoke during pregnancy are more likely to have newborns with lower birth weight, increasing the risk of health complications.2

Infants exposed to secondhand smoke after birth are at greater risk for Sudden Infant Death Syndrome (SIDS).1,2,3

  • 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.9
  • Smoking by women during pregnancy increases the risk for SIDS.1,3,10
  • Chemicals in secondhand smoke appear to affect the brain in ways that interfere with its regulation of infants’ breathing.1,3
  • 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.1,3

Parents can help protect their babies from SIDS by taking the following three actions:11

  • Do not smoke during pregnancy.
  • Do not smoke or allow smoking in your home or around your baby.
  • Place your baby on his or her back for all sleep times—naps and at night.

Secondhand Smoke Causes Health Problems in Children

girl with asthma breathing treatment

Secondhand smoke can cause serious health problems in children.1,2,3

  • Studies show that older children whose parents smoke get sick more often. They grow up with lungs weaker than children not exposed to secondhand smoke, and they get more bronchitis and pneumonia.3
  • Wheezing, coughing, and shortness of breath are more common in children exposed to secondhand smoke.3
  • 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.3
  • 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. 3

Parents can help protect their children from secondhand smoke by taking the following actions:12

  • 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.

For Further Information
Centers for Disease Control and Prevention
National Center for Chronic Disease Prevention and Health Promotion
Office on Smoking and Health
E-mail: tobaccoinfo@cdc.gov
Phone: 1-800-CDC-INFO

Media Inquiries: Contact CDC’s Office on Smoking and Health press line at 770-488-5493.

1 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 2021 Apr 20].

2 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 2021 Apr 20].

3 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 2021 Apr 20].

4 Huang J, King BA, Babb SD, Xu X, Hallett C, Hopkins M. Sociodemographic Disparities in Local Smoke-Free Law Coverage in 10 States. American Journal of Public Health 2015;105(9):1806–13 [accessed 2021 Apr 20].

5 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 2021 Apr 20].

6 Institute of Medicine Committee on Secondhand Smoke Exposure and Acute Coronary Events. Secondhand Smoke Exposure and Cardiovascular Effects: Making Sense of the Evidence. Washington, D.C., National Academies Press 2010 [accessed 2021 Apr 20].

7 National Toxicology Program. Report on Carcinogens, Fourteenth Edition. Research Triangle Park (NC): U.S. Department of Health and Human Services, Public Health Service, 2016 [accessed 2021 Apr 20].

8 Tsai J, Homa DM, Gentzke AS, Mahoney M et al. Exposure to Secondhand Smoke Among Nonsmokers—United States, 1988-2014. MMWR 2018;67(48): 1342-46 [accessed 2021 Apr 20].

9 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 [accessed 2021 Apr 20].

10 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 2021 Apr 20].

11 Centers for Disease Control and Prevention. Sudden Unexpected Infant Death and Sudden Infant Death Syndrome: Parents and Caregivers. Centers for Disease Control and Prevention, Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion [accessed 2021 Apr 20].

12 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 2021 Apr 20].