Maryland's Tobacco Resource Center - Linking Professionals to Best Practices

Secondhand Smoke

     Secondhand Smoke (SHS) is smoke from burning tobacco products, such as cigarettes, cigars or pipes, and/or smoke that is exhaled or breathed out by the person smoking.1 It contains chemicals like benzene, cadmium, formaldehyde and tobacco-specific nitrosamines (TSNA) that have been linked to various forms of cancer.2 There is no safe level of exposure to SHS.3

Youth and SHS

     Infants and children are the most vulnerable to SHS because it can negatively affect the way they develop.4 What is more concerning is that children are most exposed to SHS in their homes. In 2010, SHS exposure at home was associated positively with emergency room visits and an estimated $62.9 million in annual healthcare costs.5 Secondhand smoke exposure causes respiratory symptoms (e.g. wheezing, phlegm and breathlessness), acute lower respiratory infections (e.g. bronchitis and pneumonia) in infants and children.6 It can also increase the risk of getting ear infections. 6 Childhood exposure to SHS as low as an hour a week has been shown to have negative health effects like higher rates of ischemic heart disease and chronic obstructive pulmonary disease in adulthood.7 Adolescents exposed to SHS were at an increased risk of having emergency department and urgent care visits, and were more likely to miss school because of illness. Evidence has also shown that SHS exposure in adolescence is associated with smoking later in life.8

For more information on youth smoking, please visit our page on Youth Smoking.

Multiunit Homes

     Residents of multiunit homes (MUH) are particularly effected due to the nature of SHS. SHS travels through various pathways like vents, electrical outlets and elevator shafts. One study found that despite individual units adopting smoke-free home rules, about one-third of residents of MUHs experienced incursions of SHS.9 The same study found that less people in MUHs adopted smoke-home free rules then people in single-family homes.9

Pregnant Women

     Pregnant women exposed to SHS were more likely to experience stillbirth, give birth to a child with a congenital malformation,10 and have babies with lower birth weight.6 Babies who were exposed to SHS in the womb as well as after birth are more likely to die from sudden infant death syndrome (SIDS). 6

For more information on the effects of smoking of pregnant women, please visit our page on Pregnancy.

The Effectiveness of Smoking Bans and Smoke-free Environments

     In 2017, over 7.6 million youth reported exclusive exposure to SHS in a public place and over 1.2 million were exclusively to secondhand aerosol (SHA), the byproduct of Electronic Nicotine Delivery Systems (ENDS).11 More than 5.4 million youth, every one in five, reported recent exposure to both SHS and SHA in public places.11 Exposure remains particularly higher among children, non-Hispanic blacks, those living in poverty and those who rent their housing.12

     Smoking bans have been shown to be effective in reducing SHS and adult smoking. There is strong evidence that they prevent cardiovascular disease in the overall population and improve respiratory outcomes among workers.13 Between 2000 and 2010, ER visits associated with SHS exposure for children dropped from $215.1 million to $62.9 million, which was linked to a drop in the prevalence of SHS exposure from 25.0% to 9.1%. 5 The International Agency for Research on Cancer World Health Organization (IARC) reports that workers in smoke-free environments are more likely to implement smoking restrictions at home.14 They also report that home smoking restrictions have greater influence on smoking patterns that smoking restrictions at the workplace.14 This is particularly important because smoking bans while effective do not cover SHS exposure in private spaces. However, partial smoking bans, where smoking is banned in some spaces but not others, have been shown to be relatively ineffective particularly in places like casinos15 and hotels16.

     Smokers homes were found to be more expensive to prepare and remained vacant longer compared to the homes of non-smokers.17 Similarly, it has been shown that cars sold by smokers lost 7 – 9% of value compared to cars of non-smokers that were equivalent in age, make, model and condition.18


1) Centers for Disease Control and Prevention. Secondhand smoke (SHS) facts. Retrieved from Accessed 14 May 2019

2) National Cancer Institute. Secondhand smoke and cancer. Retrieved from Accessed 14 May 2019

3) United States Surgeon General. The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General. Retrieved from: Accessed April 22, 2019.  Accessed 14 May 2019

4) U.S. Department of Health and Human Services. The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General: Secondhand Smoke: What It Means To You. Retrieved from: Accessed 14 May 2019

5) Yao, T., Sung, H., Wang, Y., Lightwood, J., & Max, W. (2018). Healthcare costs attributable to secondhand smoke exposure at home for U.S. adults. Preventive Medicine, 108, 41-46. doi:10.1016/j.ypmed.2017.12.028

6) Centers for Disease Control and Prevention. Smoking & tobacco use: Children in the home. Retrieved from Accessed 14 May 2019

7) Diver, W. R., Jacobs, E. J., & Gapstur, S. M. (2018). Secondhand Smoke Exposure in Childhood and Adulthood in Relation to Adult Mortality Among Never Smokers. American Journal of Preventive Medicine,55(3), 345-352. doi:10.1016/j.amepre.2018.05.005

8) Mcintire, R. K., Nelson, A. A., Macy, J. T., Seo, D., & Kolbe, L. J. (2015). Secondhand smoke exposure and other correlates of susceptibility to smoking: A propensity score matching approach. Addictive Behaviors,48, 36-43. doi:10.1016/j.addbeh.2015.04.009

9) Nguyen, K. H., Gomez, Y., Homa, D. M., & King, B. A. (2016). Tobacco Use, Secondhand Smoke, and Smoke-Free Home Rules in Multiunit Housing. American Journal of Preventive Medicine,51(5), 682-692. doi:10.1016/j.amepre.2016.05.009

10) Leonardi-Bee, J., Britton, J., & Venn, A. (2011). Secondhand Smoke and Adverse Fetal Outcomes in Nonsmoking Pregnant Women: A Meta-analysis. Pediatrics,127(4), 734-741. doi:10.1542/peds.2010-3041

11) Gentzke, A. S., Wang, T. W., Marynak, K. L., Trivers, K. F., & King, B. A. (2019). Exposure to Secondhand Smoke and Secondhand E-Cigarette Aerosol Among Middle and High School Students. Preventing Chronic Disease,16. doi:10.5888/pcd16.180531

12) Homa, D. M., Neff, L. J., King, B. A., Caraballo, R. S., Bunnell, R. E., Babb, S. D., … Wang, L. (2015). Vital signs: disparities in nonsmokers' exposure to secondhand smoke--United States, 1999-2012. MMWR. Morbidity and mortality weekly report64(4), 103–108.

13) Garcia-Esquinas, E., Jiménez, A., Pastor-Barriuso, R., Jones, M.R., Perez-Gomez, B., Navas-Acien, A., & Tellez-Plaza, M. (2018). Impact of declining exposure to secondhand tobacco smoke in public places to decreasing smoking-related cancer mortality in the US population, Environment International, 117, 260-267. doi:10.1016/j.envint.2018.05.008

14) IARC, 2009

15) Cochran, Henriques York and Lee (2012)

16) Thirdhand smoke and exposure in California hotels: non-smoking rooms fail to protect non-smoking hotel guests from tobacco smoke exposure Matt et al. (THS article)

17) Matt, G. E., Quintana, P. J., Zakarian, J. M., Fortmann, A. L., Chatfield, D. A., Hoh, E., . . . Hovell, M. F. (2010). When smokers move out and non-smokers move in: Residential thirdhand smoke pollution and exposure. Tobacco Control,20(1). doi:10.1136/tc.2010.037382

18) Matt, G. E., Romero, R., Ma, D. S., Quintana, P. J., Hovell, M. F., Donohue, M., . . . Chatfield, D. (2008). Tobacco use and asking prices of used cars: Prevalence, costs, and new opportunities for changing smoking behavior. Tobacco Induced Diseases,4(1), 2. doi:10.1186/1617-9625-4-2