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

Thirdhand Smoke

THS: What is it?

      “Thirdhand Smoke (THS) consists of residual tobacco smoke pollutants that remain on surfaces and in dust after tobacco has been smoked. These elements are re-emitted into the gas phase, or react with oxidants and other compounds in the environment to yield secondary pollutants.”1 Although the term “thirdhand” smoke is relatively new, the idea of thirdhand smoke is not. Thirdhand smoke was considered a part of secondhand (SHS) and referred to as “passive smoking” or “environmental tobacco smoke.” 2 THS exposure occurs via inhalation, ingestion, or through the skin. THS can even find its way into the homes of individuals who do not smoke through outdoor air and dust, tobacco smoke-contaminated clothing, or other articles brought into the home.3 Even in the homes of smokeless tobacco users, concentrations of tobacco-specific chemicals are at similar levels to homes of smokers, and at significantly higher levels than homes of nonsmokers.4

Why is THS a concern?

      THS has been found to contain a number of tobacco-specific carcinogens – concentrations of which have been found to increase over time from SHS exposure.3,5 This increase is likely due to a reaction between the dormant nicotine and ambient nitrous acid and oxidant gases.6

      Evidence suggests that exposure to THS may produce alterations in both animal and human cellular functions and an increase in cytotoxicity.7 It has also been reported that THS exposure can affect the development of the brain in children due to the ability of THS components to cross the blood brain barrier.8 Alterations in serotonin receptors in the brain have been linked to neuropsychiatric conditions like OCD and schizophrenia as well as impaired brain functions like sleep disorders.9

Who does THS most affect?

THS affects the most vulnerable (e.g., infants and children, the elderly, as well as pets).

“Because of the way people are most often exposed to third-hand smoke, children are particularly vulnerable. Children often crawl and play on the floor and furniture, and frequently make hand-to-mouth contact or put their mouths on household objects. Even so, many parents aren’t aware of the dangers of environmental tobacco smoke.” 10

People in multi-unit homes and public housing are also vulnerable since tobacco smoke can move through air ducts, cracks in the walls and floors, elevator shafts and other pathways.11 According to the National Multifamily Housing Council, 26% of renters and owners of multifamily homes (e.g. apartments and condominiums) are occupied by people ages 65 or older.12 Although the U.S. Department of Housing and Urban Development has placed smoking restrictions in all public housing, this still leaves residents of private multi-unit homes vulnerable if smoking bans are not placed at those residences.13

Pets like cats and dogs are vulnerable as they spend most of their time on or near the floor where THS from dust, carpets, and rugs collects.14 Pets can also ingest THS by licking their owner’s hair, skin, and clothes. Nicotine exposure in pets can cause cancer, illness and health problems much like humans.14 Cats, birds, and other pets that groom themselves are more at risk to nicotine exposure as their fur and feather are coated in THS.14

The need for research and awareness

While the research behind THS is growing, many researchers believe that more needs to be done concerning the long-term effects of THS and its effects in the pediatric population.1,7

Public awareness is important to emphasize especially when studies have shown that more than half of the population is unaware of THS and its health risks.7 Similarly, according to the American Academy of Pediatrics, only 43% of smokers and 65% of non-smokers believe that THS causes harm to children.15

One potential area of focus should be on educating providers and health professionals on informing the public of the risks of THS. One study found that up to one-third of health professionals had heard about THS and that two-thirds of the health professionals believed that THS issues do not receive enough attention prior to taking their survey.16 They state in their discussion that by educating providers about the dangers of THS, this may shape the perceptions of smoking restrictions and improve harm reduction advice practices.

For more information about Thirdhand Smoke and how to prevent it please visit the website for the Thirdhand Smoke Resource Center.


1Matt, G. E., Quintana, P. J., Destaillats, H., Gundel, L. A., Sleiman, M., Singer, B. C., … Hovell, M. F. (2011). Thirdhand tobacco smoke: emerging evidence and arguments for a multidisciplinary research agenda. Environmental health perspectives, 119(9), 1218–1226. doi:10.1289/ehp.1103500

2Bell, K. (2014). Science, policy and the rise of ‘thirdhand smoke’ as a public health issue, Health, Risk & Society, 16(2), 154-170. doi: 10.1080/13698575.2014.884214

3Jacob, P., Benowitz, N. L., Destaillats, H., Gundel, L., Hang, B., Martins-Green, M., … Whitehead, T. P. (2016 – LISTED AS 2017 IN TEXT. Thirdhand Smoke: New Evidence, Challenges, and Future Directions. Chemical research in toxicology, 30(1), 270–294. doi:10.1021/acs.chemrestox.6b00343

4Whitehead, T. P., Havel, C., Metayer, C., Benowitz, N. L., & Jacob, P. (2015). Tobacco alkaloids and tobacco-specific nitrosamines in dust from homes of smokeless tobacco users, active smokers, and nontobacco users. Chemical research in toxicology, 28(5), 1007–1014. doi:10.1021/acs.chemrestox.5b00040

5Schick, S.F., Glantz, S., 2007. Concentrations of the carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1- butanone in sidestream cigarette smoke increase after release into indoor air: results from unpublished tobacco industry research. Cancer Epidemiol Biomark & Prevention, 16 (8), 1547–1553.

6Sleiman, M., Gundel, L. A., Pankow, J. F., Jacob, P., Singer, B. C., & Destaillats, H. (2010). Formation of carcinogens indoors by surface-mediated reactions of nicotine with nitrous acid, leading to potential thirdhand smoke hazards. Proceedings of the National Academy of Sciences of the United States of America, 107(15), 6576–6581. doi:10.1073/pnas.0912820107

7Díez-Izquierdo, A., Cassanello-Peñarroya, P., Lidón-Moyano, C., Matilla-Santander, N., Balaguer, A., & Martínez-Sánchez, J. M. (2018). Update on thirdhand smoke: A comprehensive systematic review. Environmental Research, 167, 341-371. doi:10.1016/j.envres.2018.07.020

8Bahl, V., Johnson, K., Phandthong, R., Zahedi, A., Schick, S.F., & Talbot, P. (2016). Thirdhand cigarette smoke causes stress-induced mitochondrial hyperfusion and alters the transcriptional profile of stem cells. Toxicological Sciences, 153(1), 55-69. doi: 10.1093/toxsci/kfw102

9 Mazzone, P., Tierney, W., Hossain, M., Puvenna, V., Janigro, D., & Cucullo, L. (2010). Pathophysiological Impact of Cigarette Smoke Exposure on the Cerebrovascular System with a Focus on the Blood-brain Barrier: Expanding the Awareness of Smoking Toxicity in an Underappreciated Area. International Journal of Environmental Research and Public Health,7(12), 4111-4126. doi:10.3390/ijerph7124111

10Halsted, C., & Pew, A. (2018, May 23). Third-Hand Smoke. National Center for Health Research. Retrieved from

11 Spengler J. D. (1999). Buildings operations and ETS exposure. Environmental health perspectives, 107 Suppl 2(Suppl 2), 313–317. doi:10.1289/ehp.99107s2313

12 U.S. Department of Housing and Urban Development. 2019. Resident Characteristics Report. Available Accessed 8 April 2019

13 U.S. Department of Housing and Urban Development. 2016. Instituting Smoke-Free Public Housing. Retrieved from

14U.S. Food and Drug Administration. 2017. Be smoke-free and help your pets live longer, healthier lives. Retrieved from Accessed 23 May 2019

15 American Academy of Pediatrics (2017, April 24). How Parents Can Prevent Exposure to Thirdhand Smoke. Retrieved from Accessed 8 April 2019

16Darlow, S. D., Heckman, C. J., Munshi, T., & Collins, B. N. (2016). Thirdhand smoke beliefs and behaviors among healthcare professionals. Psychology, health & medicine, 22(4), 415–424. doi:10.1080/13548506.2016.1189579