Second-hand Tobacco Smoke Exposure
In a comprehensive meta-analysis of ten cohort studies and eight case–control studies involving around half a million participants, He et al. found that second-hand smoke (SHS) exposure was associated with a 25% increase in the risk of acquiring coronary heart disease and its sequelae.[76] SHS also contributes to the progression of atherosclerosis and is associated with increased infarct size in smokers who experience a myocardial infarction.[77] In their review of the literature on the association of SHS with cardiovascular disease, Law et al. found that nonsmokers exposed to smoke from smoking spouses experience on average a 30% excess risk of ischemic heart disease death and of nonfatal AMI.[19] SHS has also been implicated as a causal factor in stroke for males and females in several well-conducted epidemiological studies[78–81] but the association with duration and amount of exposure is unclear to date.[81]
Second-hand smoke is largely derived from the side stream smoke of other's cigarettes and is qualitatively different from the mainstream smoke inhaled by smokers through their own cigarette. Side stream smoke is far more toxic, with concentrations of known toxins such as oxidant gases higher by several multiples than mainstream smoke.[41] Thus, the mechanisms of action are the same with SHS as those in active smoking but the effects are magnified out of proportion to exposure: despite an exposure to tobacco smoke of less than 1% of the exposure from smoking 20 cigarettes per day the excess risk is as much as a third of that of a smoker of 20 cigarettes per day.[9]
Expert Rev Cardiovasc Ther. 2008;6(6):883-895. © 2008 Expert Reviews Ltd.
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Cite this: Impact of Tobacco Smoking and Smoking Cessation on Cardiovascular Risk and Disease - Medscape - Jun 01, 2008.
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