4.3 Thirdhand smoke and other indirect sources of secondhand smoke

Thirdhand smoke is a new area of investigation in tobacco control and studies are few. Thirdhand smoke refers to exposure to chemicals from secondhand smoke that have deposited on indoor surfaces.1 Research shows that smoking in the home is associated with persistent high levels of tobacco toxins long after smoking has ended.1,2 Vapour phase constituents adsorb onto walls, furniture, clothes, toys and other objects within 10 minutes to hours after a cigarette has been smoked inside the house.3 From there, they are re-emitted into the air over the course of hours, weeks and months.1,3 Particulate matter from secondhand smoke settles and coats household surfaces and contaminates dust, where it may react with vapour phase compounds or, to a small extent, become re-suspended in the air.3,4

Thirdhand smoke accumulates in smokers' homes, with dust and surfaces being the two major reservoirs. One study found nicotine levels 12 to 21 times higher in dust and 30 to 150 times higher on surfaces in smokers' homes compared to non-smokers' homes.2 Infants of smoking parents are particularly exposed to thirdhand smoke as they spend much time indoors and tend to be active near the floor, close to the contaminated dust, carpets, blankets and other objects. They frequently put objects in their mouths, and tend to ingest more dust than adults. They also tend to be in close physical contact with their smoking parents, whose clothes, hair and skin tend to be coated with thirdhand smoke.3 Nicotine levels remained higher in former homes of smokers two months after being vacated, cleaned and prepared for new residents.2 Nicotine levels on the fingers of non-smokers who moved into former homes of smokers were seven to eight times higher than those in non-smoker homes.2

Limited evidence shows that thirdhand smoke contains toxic substances but further research is needed to establish what level of harm it presents. Nicotine adsorbed onto indoor surfaces reacts with nitrous acid in the air to form tobacco-specific nitrosamines, which are potent carcinogens.5 It is not known whether these nitrosamines react to form other compounds or whether they build up with time. However, they are quite stable in indoor conditions and so have the potential to accumulate.6,7 Ultrafine particles are also produced through the oxidative ageing of secondhand smoke.8

Further research is needed to establish the content of thirdhand smoke, how long it persists, how much it contributes to exposure to tobacco pollution overall, and what impact it has on human health.7

4.3.1 Other sources of indirect exposure to secondhand smoke

Maintaining a total ban on smoking indoors greatly reduces non-smokers' exposure to secondhand smoke. However, even with indoor smoking bans, parents who smoke have been unable to reduce the levels of secondhand smoke contamination in their home, and secondhand smoke exposure of their children, to levels in households where nobody smokes.3,9,10 This may be partly due to the persistence of thirdhand smoke from past smoking indoors, or from contaminated clothing, skin and dust carried into the home.3 Other sources of indirect exposure to secondhand smoke include smoke drift from outdoors and residual tobacco smoke coming from the lungs of a smoker after they have finished a cigarette.3,11 It is estimated to take three minutes to clear volatile organic compounds and 90 seconds or up to 13 subsequent breaths to clear out fine particles from a smoker's lung after smoking.11 The concentration of residual tobacco smoke from smokers' lungs is low and may be a concern only to particularly sensitive persons or when adding to already raised indoor pollution levels.11 Smoke drift from adjacent outdoor areas may significantly raise indoor measurements of secondhand smoke and compromise the air quality of smokefree indoor areas.12,13

4.3.2 How parents can keep their homes smokefree

The best advice for health professionals to give to parents who smoke is to quit in order to make their homes a completely smokefree environment.10 For parents who are not ready to quit, the most effective way to reduce their children's exposure to secondhand smoke is by always smoking outdoors after closing doors and windows, and smoking away from their children when outdoors.3,9,14

Recent news and research

For recent news items and research on this topic, click here (Last updated January 2017)   

References

1. Winickoff J, Friebely J, Tanski S, Sherrod C, Matt G, Hovell M, et al. Beliefs about the health effects of 'thirdhand' smoke and home smoking bans. Pediatrics 2009;123(1):e74–9. Available from: http://pediatrics.aappublications.org/cgi/content/full/123/1/e74

2. Matt GE, Quintana PJ, Zakarian JM, Fortmann AL, Chatfield DA, Hoh E, et al. When smokers move out and non-smokers move in: residential thirdhand smoke pollution and exposure. Tobacco Control 2011;20(1):e1. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21037269

3. Matt GE, Quintana PJE, Hovell MF, Bernert JT, Song S, Novianti N, et al. Households contaminated by environmental tobacco smoke: sources of infant exposures. Tobacco Control 2004;13(1):29–37. Available from: http://tobaccocontrol.bmj.com/cgi/content/abstract/13/1/29

4. Becquemin MH, Bertholon JF, Bentayeb M, Attoui M, Ledur D, Roy F, et al. Third-hand smoking: indoor measurements of concentration and sizes of cigarette smoke particles after resuspension. Tobacco Control 2010;19:(4):347–8. Available from: http://tobaccocontrol.bmj.com/content/19/4/347.shortÂ

5. Sleiman M, Gundel LA, Pankow JF, Jacob P, 3rd, Singer BC and Destaillats H. 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 USA 2010;107(15):6576-81. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20142504

6. Dreyfuss JH. Thirdhand smoke identified as potent, enduring carcinogen. CA A Cancer Journal for Clinicians 2010;60(4):203-4. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20530799

7. Schick S. Thirdhand smoke: here to stay. Tobacco Control 2011;20(1):1–3. Available from: http://tobaccocontrol.bmj.com/content/20/1/1.short

8. Sleiman M, Destaillats H, Smith JD, Liu C-L, Ahmed M, R WK, et al. Secondary organic aerosol formation from ozone-initiated reactions with nicotine and secondhand tobacco smoke. Atmospheric Environment 2010; 34(44)4191–8 Available from: http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6VH3-50N38RB-1-7&_cdi=6055&_user=10&_pii=S1352231010005923&_orig=search&_coverDate=07%2F29%2F2010&_sk=999999999&view=c&wchp=dGLbVtb-zSkWb&md5=61539e26b8b5024fa611fb55e36099fb&ie=/sdarticle.pdf

9. Johansson A, Hermansson G and Ludvigsson J. How should parents protect their children from environmental tobacco-smoke exposure in the home? Pediatrics 2004;113(4):e291–5. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15060255

10. Rumchev K, Jamrozik K, Stick S and Spickett J. How free of tobacco smoke are 'smoke-free' homes? Indoor Air 2008;18(3):202–8. Available from: http://www.ncbi.nlm.nih.gov/pubmed/18336533

11. Invernizzi G, Ruprecht A, De Marco C, Paredi P and Boffi R. Residual tobacco smoke: measurement of its washout time in the lung and of its contribution to environmental tobacco smoke. Tobacco Control 2007;16(1):29–33. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17297070

12. Brennan E, Cameron M, Warne C, Durkin S, Borland R, Travers MJ, et al. Secondhand smoke drift: examining the influence of indoor smoking bans on indoor and outdoor air quality at pubs and bars. Nicotine & Tobacco Research 2010;12(3):271–7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20097839

13. Kaufman P, Zhang B, Bondy SJ, Klepeis N and Ferrence R. Not just 'a few wisps': real-time measurement of tobacco smoke at entrances to office buildings. Tobacco Control 2011;20(3):212–8. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21177666

14. Wakefield M, Banham D, Martin J, Ruffin R, McCaul K and Badcock N. Restrictions on smoking at home and urinary cotinine levels among children with asthma. American Journal of Preventive Medicine 2000;19(3):188–92. Available from: http://www.ncbi.nlm.nih.gov/pubmed/11020596

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