do not negate the evidence of an association between smoking bans and the incidence of acute MI or, for the relevant studies, secondhand-smoke exposure and the incidence of acute MI. As a consequence of the variability and the limitations, however, it is difficult to use them to estimate the magnitude of the effect of smoking bans or secondhand-smoke exposure on the incidence of acute MI.


  • The extent to which the studies assessed possible alternative causes of changes in hospitalizations—health-care availability, use of different cardiac medications, new diagnostic criteria, and a decrease in all hospital admissions during a period—should be considered, especially if before–after comparisons are being made in the absence of a comparison area. Given the multiple factors that could affect the rate of acute MIs, however, an assessment of secular trends is preferable.

  • Results of studies that included self-reported assessments of exposure to secondhand smoke cannot necessarily be compared with results of other studies that did the same thing unless the survey instruments (such as interviews) were similar.

  • All the studies are relevant and informative with respect to the questions posed to the committee, and overall they support an association between smoking bans and a decrease in acute cardiovascular events.

  • The magnitude of the effect cannot be determined on the basis of the studies, because of variability among and uncertainties within them.

  • In most of the studies, the portion of the effect attributable to decreased smoking by smokers as opposed to decreased exposure of nonsmokers to secondhand smoke cannot be determined.

  • The studies support, to the extent that it was evaluated, an association between a reduction in secondhand smoke and a decrease in acute cardiovascular events. The strongest data on that association in nonsmokers come from

    • Analyses of only nonsmokers (Monroe, Indiana, and Scotland).

    • Analyses that showed decreases in secondhand smoke after implementation of smoking bans.

  • At the population level, results of the key intervention studies reviewed by the committee are for the most part consistent with a decrease in risk as early as a month following reductions in secondhand-smoke exposure; however, given the variability in the

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