Secondhand Smoke (SHS) Facts
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, of which hundreds are toxic and about 70 can cause cancer.1,2,3,4
There is no risk-free level of secondhand smoke exposure; even brief exposure can be harmful to health.1,2,6 Comprehensive smokefree policies have been successful in protecting those who do not smoke, and are the only way to fully protect their health.1,2,7
Health Effects in Adults
In adults who have never smoked, secondhand smoke can cause:
- Heart disease
- For adults who do not smoke, breathing secondhand smoke has immediate harmful effects on the heart and blood vessels.1,4,6
- 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, experience a 25-30% increase in their risk of developing heart disease. 1
- Lung cancer1,8
- Secondhand smoke exposure causes more than 7,300 deaths from lung cancer among people who do not smoke.1
- Each year, more than 8,000 deaths from stroke can be attributed to secondhand smoke.1
Chronic diseases such as these are the leading causes of death and disability in the United States. They may also increase risk with respect to other illnesses.1
Health Effects in Infants and Children
- Smoking during pregnancy results in more than 1,000 infant deaths annually.1
- Adults 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 have significantly higher risk of Sudden Infant Death Syndrome (SIDS).1,2,3
- Chemicals in secondhand smoke appear to affect the brain in ways that interfere with its regulation of infants’ breathing.2,3
- Infants who die from SIDS have higher concentrations of nicotine in their lungs and higher levels of cotinine than infants who die from other causes.2,3
- Exposure to secondhand smoke causes multiple health problems in infants and young children, including: 1,2,3
- Ear infections
- Respiratory symptoms (coughing, wheezing, shortness of breath)
- Acute lower respiratory infections, such as bronchitis and pneumonia
- Children with asthma who encounter secondhand smoke have more severe and more frequent asthma attacks. 1,2,3
- Secondhand Smoke
- Health Effects of Secondhand Smoke
- Secondhand Smoke Exposure Has Decreased Over Time
- Disparities in Secondhand Smoke Exposure
- Black Americans Still Face Significant Secondhand Smoke Exposure
- Secondhand Smoke Exposure is Higher Among People with Low Incomes
- Disparities in Exposure Persist Depending on Occupation
- Housing Remains a Major Source of Secondhand Smoke Exposure for Children
- Benefits of Comprehensive Smokefree Policies
- Measurements of blood serum cotinine (as a measure of secondhand exposure among people who do not smoke) show that exposure to secondhand smoke steadily decreased in the United States between 1988-2014.5
- During 1988–1991, almost 90 of every 100 (87.9%) people who did not smoke had measurable levels of cotinine.5
- During 2007–2008, about 40 of every 100 (40.1%) people who did not smoke had measurable levels of cotinine.5
- During 2011–2014, about 25 of every 100 (25.2%) people who did not smoke had measurable levels of cotinine.5
- The decline in secondhand smoke exposure among people who do not smoke is likely due to:5
- Decreasing cigarette smoking rates
- Increased awareness of the risks for secondhand smoke exposure
- The adoption of comprehensive smoke-free laws prohibiting smoking in workplaces and public places in many states and localities
- Many people who do not smoke are still exposed to secondhand smoke.
- During 2013-2014, 58 million people who do not smoke were exposed to secondhand smoke.5
Additional progress is being made as states and communities adopt comprehensive smokefree laws, but disparities in coverage of smokefree laws persists. Those of lower socioeconomic status and lower educational attainment remain less likely to be covered by smokefree laws in worksites, restaurants, and bars.5 Additionally, private settings such as homes and vehicles remain major sources of exposure for some populations, including youth.
Comprehensive smokefree laws for all workplaces and public places – without exception – and smokefree rules for homes and vehicles can fully protect nonsmokers. These policies also can help prevent youth initiation and help those who currently smoke to quit.3,4,5
Although the number of people who do not smoke but are exposed to secondhand smoke has declined, disparities in secondhand smoke exposure persist. 5
Non-Hispanic Black Americans; people who live below the federal poverty level; those who work in traditionally “blue collar” industries, service occupations, or construction; people who live in multi-unit housing; and children 3-11 years of age are more likely than other groups to be exposed to secondhand smoke.5
- Reasons for these disparities may include
- Variations in smoking prevalence
- Variations in smokefree policy coverage
- Tobacco industry misinformation. According to a legal judgment, tobacco companies “deliberately deceived the American public about the health effects of secondhand smoke.”9
- Prevalence of secondhand smoke exposure among non-Hispanic Black people who do not smoke (50.3%) is much higher compared with non-Hispanic white people (21.4%) and Americans of Mexican descent (20.0%).5
- While secondhand smoke exposure among US youths in homes and vehicles significantly declined during 2011 through 2018, secondhand smoke exposure in homes among non-Hispanic black students did not change.10
- Non-Hispanic Black middle and high school students have a higher prevalence of secondhand smoke exposure in the home (28.4%) and in vehicles (26.4%) than Hispanic (17.6%) and non-Hispanic other (14.0%) students.10
- Between 2013-2014, prevalence of secondhand smoke exposure was higher among those who lived below the federal poverty level (47.9 %) than those who lived at or above the poverty level (21.2%).
- For adults who do not smoke, the workplace remains the source of most secondhand smoke exposure.5
- Workers who do not smoke and live in states or municipalities without comprehensive smokefree policies were most likely to be frequently exposed to secondhand smoke.12
- Workers in certain industries reported more frequent secondhand smoke exposure, especially those in outdoor work environments or other work settings unlikely to be covered by workplace smokefree protections. 12
- According to a survey, those working in industrial machinery or equipment repair had 65.1% prevalence of workplace secondhand smoke exposure, the highest out of all industries.12
- The industry with the highest number of workers who do not smoke but reported exposure was construction, with 2.9 million exposed. 12
- Those who do not smoke and work in private worksites, restaurants, or bars in states with comprehensive workplace smokefree policies had significantly lower prevalence (8.6%) of frequent exposure to secondhand smoke than those in the same industry in states without comprehensive smokefree protections (12.2%).12
- Children still have a higher prevalence of secondhand smoke exposure than adults, and most are exposed in the home.5 In 2019, an estimated 6.7 million (25.3%) of middle and high school students reported secondhand smoke exposure in the home.
- 73% of children who lived with a person who smoked inside the home were exposed to secondhand smoke during 2013-2014, compared with those who did not (22.3%).5
- Children who live in multi-unit housing are more likely to be exposed to secondhand smoke.
- An estimated 80 million people—or 25% of the population—in the United States live in multi-unit housing.13
- Among children who live in homes in which no one smokes indoors, those children living in multi-unit housing such as apartments or condos have 45% higher cotinine levels than children living in single-family homes.11
- Even when no one in the unit smokes, secondhand smoke can filter into other units via hallways, stairwells, and ventilation systems.11
- Secondhand smoke exposure during 2013-2014 was higher among people who rented (38.6% their homes than those who owned their homes (19.2%).5
- Policies prohibiting smoking in housing, coupled with cessation information, could encourage people who smoke to quit, and thereby reduce secondhand smoke exposure.14
Studies show that adoption of comprehensive smokefree policies:
- Reduces secondhand smoke exposure
- Reduces smoking and encourages people who smoke to quit
- Helps prevent smoking initiation
- Does not negatively impact the hospitality industry
- Results in high levels of compliance in the state or community in which the policies are applied
Find discussions of these benefits in greater depth on the following fact sheets:
- 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 Feb 21].
- 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 Feb 21].
- 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 Feb 21].
- 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 2017 Feb 21].
- 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 2020 Sep 8].
- Institute of Medicine Committee on Secondhand Smoke Exposure and Acute Coronary Events. Secondhand Smoke Exposure and Cardiovascular Effects: Making Sense of the Evidenceexternal icon. Washington, D.C., National Academies Press 2010 [accessed 2020 Nov 30].
- National Toxicology Program. Report on Carcinogens, Fourteenth Editionexternal icon. Research Triangle Park (NC): U.S. Department of Health and Human Services, Public Health Service, 2016 [accessed 2017 Feb 21].
- Centers for Disease Control and Prevention. Vital Signs: Nonsmokers’ Exposure to Secondhand Smoke—United States, 1999–2008. Morbidity and Mortality Weekly Report 2010;59(35):1141–6 [accessed 2017 Feb 21].
- S. v. Philip Morris et al. Second Superseding Consent Order Implementing the Corrective Statements Remedy for Newspapers and Televisionexternal icon. U.S. District Court for the District of Columbia, October 5, 2017 [accessed 2020 Nov 30].
- Walton K, Gentzke AS, Murphy-Hoefer R, Kenemer B, Neff LJ. Exposure to Secondhand Smoke in Homes and Vehicles Among US Youths, United States, 2011-2019. Preventing Chronic Disease 2020(17) [accessed 2020 Oct 13].
- Wilson KM, Klein JD, Blumkin AK, Gottlieb M, Winickoff JP .Tobacco Smoke Exposure in Children Who Live in Multiunit Housing.external icon Pediatrics 2011:127(1):85-92 [accessed 2017 Feb 21].
- Su C, Syamlal G, Tamers S, Li J, Luckhaupt SE. Workplace Secondhand Tobacco Smoke Exposure Among Nonsmoking Workers, 2015. MMWR 2019;68(27): 604-607 [accessed 2020 Sep 9].
- King BA, Babb SD, Tynan MA, Gerzoff RB. National and state estimates of secondhand smoke infiltration among U.S. multiunit housing residents. Nicotine and Tobacco Research 2013a;15(7):1316–21.
- Levy DT, Borland R, Villanti AC, Niaura R, Yuan Z, Zhang Y, Meza R, Holford TR, Fong GT, Cummings KM, et al. The application of a decision-theoretic model to estimate the public health impact of vaporized nicotine product initiation in the United Statesexternal icon. Nicotine and Tobacco Research 2017;19(2): 149-159 [accessed 2020 Sep 9].