Studies of the effect of indoor smoking bans and secondhand-smoke exposure on acute coronary events should be designed to examine the time between an intervention and changes in the effect and to measure the magnitude of the effect. No time to effect can be postulated for individuals on the basis of the available data, and evaluation of population-based effectiveness of a smoking ban depends on societal actions that implement and enforce the ban and on actions that include smoke reduction in homes, cars, and elsewhere. The decrease in secondhand-smoke exposure does not necessarily occur suddenly—it might decline gradually or by steps. In a likely scenario, once a ban is put into place and enforced, a sharp drop in secondhand-smoke exposure might be seen immediately and followed by a slower decrease in exposure as the population becomes more educated about the health consequences of secondhand smoke and exposure becomes less socially acceptable. Future studies that examine the time from initiation of a ban to observation of an effect and that include followup after initiation of enforcement, taking the social aspects into account, would provide better information on how long it takes to see an effect of a ban. Statistical models should clearly articulate a set of assumptions and include sensitivity analyses. Studies that examine whether decreases in hospital admissions for acute coronary events are transitory or sustained would also be informative.
Many factors are likely to influence the effect of a smoking ban on the incidence and prevalence of acute coronary events in a population. They include age, sex, diet, background risk factors and environmental factors for cardiovascular disease, prevalence of smokers in the community, the underlying rate of heart disease in the community (for example, the rate in Italy versus the United States), and the social environment. Future studies should include direct observations on individuals—including their history of cardiac disease, exposure to other environmental agents, and other risk factors for cardiac events—to assess the impact of those factors on study results. Assessment of smoking status is also needed to distinguish between the effects of secondhand smoke in nonsmokers and the effects of a ban that decreases cigarette consumption or promotes smoking cessation in smokers.
Few constituents of secondhand smoke have been adequately studied for cardiotoxicity. Future research should examine the cardiotoxicity of environmental chemicals, including those in secondhand smoke, to define cardiovascular toxicity end points and establish consistent definitions and measurement standards for cardiotoxicity of environmental contaminants. Specifically, information is lacking on the cardiotoxicity of highly reactive smoke constituents, such as acrolein and other oxidants; on techniques for