4.6 Cardiovascular disease and secondhand smoke

4.6.1 Coronary heart disease

Exposure to secondhand smoke is a cause of coronary heart disease (also known as ischaemic heart disease) in non-smokers.1,3

Secondhand smoke affects the cardiovascular system in non-smokers by multiple mechanisms, similar to those experienced by active smokers.3 Secondhand smoke activates blood platelets, which increases the risk of thrombosis and damages the cellular lining of the arteries, which promotes atherosclerosis.3,4 Secondhand smoke increases arterial stiffness, and affects the ability of arteries to properly expand and contract in order to regulate blood flow. Exposure to secondhand smoke is associated with changes in lipoprotein profiles, including lower blood levels of high density lipoprotein (HDL), a 'good' cholesterol, which plays an important role in preventing the progression of atherosclerosis.4 Other mechanisms mediated by secondhand smoke that contribute to cardiovascular disease include increased oxidative stress and decreased antioxidant defence, infection and inflammation, decreased energy production in the heart muscle, and a decrease in heart rate variability.3,4 Most of these responses occur rapidly following exposure.35 Where underlying cardiovascular disease already exists, exposure to secondhand smoke exacerbates the condition. Individuals with underlying diabetes, vascular disease or hypertension are at greater risk of harm from secondhand smoke.

It is estimated that exposure to secondhand smoke increases the risk of an acute heart disease event in the non-smoker by about one-quarter to one-third.2,3,6,7 In comparison, active smokers have an increased risk of one-half to four-fold, depending on quantity smoked, age and gender.8 Thus the increased risk for exposed non-smokers is approaching the risk of active smoking, even though a non-smoker's actual exposure to tobacco smoke is far less than that of the active smoker.3,9 British research suggests that taking into account all sources of exposure, secondhand smoke may account for an excess risk of up to 60% for coronary heart disease in heavily exposed non-smokers, a rate similar to that of active smokers of up to 10 cigarettes per day.10

Due to the extreme sensitivity of the cardiovascular system to comparatively low exposures of tobacco smoke, secondhand smoke can cause a disproportionately high amount of damage. For non-smokers, even brief exposures to secondhand smoke (ranging from minutes to hours) may have 80–90% of the effect of active smoking on some cardiovascular mechanisms, including platelet activation and arterial vasodilation.3,4,11 For smokers, secondhand smoke does not induce additional effects for these processes, suggesting that they may become saturated at doses experienced by exposed non-smokers.11,9 This saturation effect may contribute to the non-linear relationship between tobacco smoke exposure and heart disease events described in Section 4.5: Mechanisms of disease.6,11

4.6.2 Stroke

Current evidence suggests that secondhand smoke may contribute to an increased risk of stroke, through encouraging atherosclerosis in the carotid and large arteries of the brain, and damaging arteries within the brain. However further research is required before this finding can be confirmed.2,3

4.6.3 Other cardiovascular disease

Evidence suggests that secondhand smoke contributes to an increased risk of atherosclerosis.3 Studies suggest that secondhand smoke is damaging for a number of sub-clinical vascular outcomes, in particular carotid arterial wall thickening. However further research is required before this association can be confirmed as causal.3

Cardiovascular disease is a known risk factor for dementia.12,13 Preliminary studies indicate a link between secondhand smoke exposure and dementia or cognitive decline, particularly among those with symptoms of cardiovascular disease.12,14 Further research is needed to confirm an association between dementia and secondhand smoke.12,14

4.6.4 Exposure to secondhand smoke in children and cardiovascular disease

A limited number of studies suggest that children exposed to secondhand smoke show preclinical signs of atherosclerosis. These include lower blood levels of HDL, reduced aortic elasticity and levels of plasma biomarkers indicating a low-grade inflammatory response.2,3,15,16 Two studies found that children exposed to tobacco smoke had increased thickness of the walls of the carotid and aortic arteries, with one study linking it to long-term exposure to secondhand smoke,17 and the other to parental smoking during pregnancy.18 More research is needed to confirm these associations and elucidate their potential contribution to cardiovascular disease.

Recent news and research

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

References

1. Scientific Committee on Tobacco and Health. Report of the Scientific Committee on Tobacco and Health. London: UK Department of Health, 1998. Available from: http://www.archive.official-documents.co.uk/document/doh/tobacco/contents.htm

2. Office of Environmental Health Hazard Assessment and California Air Resources Board. Health effects of exposure to environmental tobacco smoke: final report, approved at the Panel's June 24, 2005 meeting. Sacramento: California Environmental Protection Agency, 2005. Available from: http://www.oehha.ca.gov/air/environmental_tobacco/2005etsfinal.html

3. US Department of Health and Human Services. The health consequences of involuntary exposure to tobacco smoke: a report of the Surgeon General. Atlanta, Georgia: US Department of Health and Human Services, Centers for Disease Control and Prevention, Coordinating Center for Health Promotion, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2006. Available from: http://www.cdc.gov/tobacco/data_statistics/sgr/sgr_2006/index.htm

4. Barnoya J and Glantz S. Cardiovascular effects of secondhand smoke: nearly as large as smoking. Circulation 2005;111:2684–98. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15911719

5. Raupach T, Schafer K, Konstantinides S and Andreas S. Secondhand smoke as an acute threat for the cardiovascular system: a change in paradigm. European Heart Journal 2006;27:386–92. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16230308

6. Law M and Wald N. Environmental tobacco smoke and ischemic heart disease. Progress in Cardiovascular Diseases 2003;46:31–8. Available from: http://www.ncbi.nlm.nih.gov/pubmed/12920699

7. Teo KK, Ounpuu S, Hawken S, Pandey MR, Valentin V, Hunt D, et al. Tobacco use and risk of myocardial infarction in 52 countries in the INTERHEART study: a case-control study. Lancet 2006;368(9536):647–58. Available from: http://www.ncbi.nlm.nih.gov/entrez/pubmed/16920470

8. International Agency for Research on Cancer. Reversal of risk after quitting smoking. Handbooks of cancer prevention, tobacco control, Vol. 11. Lyon, France: IARC, 2007. Available from: http://apps.who.int/bookorders/anglais/detart1.jsp?sesslan=1&codlan=1&codcol=76&codcch=22

9. Glantz SA and Parmley WW. Even a little secondhand smoke is dangerous. Journal of the American Medical Association 2001;286(4):462–3. Available from: http://www.ncbi.nlm.nih.gov/pubmed/11466127

10. Whincup PH, Gilg JA, Emberson JR, Jarvis MJ, Feyerabend C, Bryant A, et al. Passive smoking and risk of coronary heart disease and stroke: prospective study with cotinine measurement. British Medical Journal 2004;329:200–5. Available from: http://www.bmj.com/cgi/content/full/329/7459/200

11. Smith K and Peel J. Mind the Gap. Environmental Health Perspectives 2010;18(12) Available from: http://ehp03.niehs.nih.gov/article/info:doi/10.1289/ehp.1002517

12. Barnes D, Haight T, Mehta K, Carlson M, Kuller L and Tager I. Secondhand smoke, vascular disease, and dementia incidence: findings from the cardiovascular health cognition study. American Journal of Epidemiology 2010;171(3):292–302. Available from: http://aje.oxfordjournals.org/cgi/content/full/171/3/292

13. Barrett JR. Dementia and secondhand smoke. Environmental Health Perspectives 2007;115(8):A401. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17687426

14. Llewellyn D, Lang I, Langa K, Naughton F and Matthews F. Exposure to secondhand smoke and cognitive impairment in non-smokers: national cross sectional study with cotinine measurement. BMJ (Clinical Research Ed.) 2009;338:b462. Available from: http://www.bmj.com/cgi/content/full/338/feb12_2/b462?view=long&pmid=19213767

15. Metsios G, Flouris A, Angioi M and Koutedakis Y. Passive smoking and the development of cardiovascular disease in children: a systematic review. Cardiology Research and Practice 2010;2011 Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2945638/?tool=pubmed

16. Nagel G, Arnold F, Wilhelm M, Link B, Zoellner I and Koenig W. Environmental tobacco smoke and cardiometabolic risk in young children: results from a survey in South-West Germany. European Heart Journal 2009;30(15):1885–93. Available from: http://eurheartj.oxfordjournals.org/content/30/15/1885.long

17. Kallio K, Jokinen E, Saarinen M, Hamalainen M, Volanen I, Kaitosaari T, et al. Arterial intima-media thickness, endothelial function, and apolipoproteins in adolescents frequently exposed to tobacco smoke. Circulation. Cardiovascular Quality and Outcomes 2010;Epub ahead of print. Available from: http://circoutcomes.ahajournals.org/cgi/rapidpdf/CIRCOUTCOMES.109.857771v1

18. Geerts C, Bots M, Grobbee D and Uiterwaal C. Parental smoking and vascular damage in young adult offspring: is early life exposure critical? The atherosclerosis risk in young adults study. Arteriosclerosis, Thrombosis, and Vascular Biology 2008;28(12):2296–302. Available from: http://atvb.ahajournals.org/cgi/content/full/28/12/2296

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