The American Heart Association has apparently concluded that an observed 27% decline in heart attack admissions in Pueblo, Colorado within 18 months of implementation of a smoking ban is attributable to a reduction in secondhand smoke exposure.
In an article in the Pueblo Chieftain, the American Heart Association president stated: "The development of atherosclerosis that leads to a heart attack usually takes 20 years. The decline in the number of heart attack hospitalizations within the first year-and-a-half after the smoking ban that was observed in this study is most likely due to a decrease in the effect of secondhand smoke as a triggering factor for heart attacks. The ordinance will likely continue to decrease the number of heart attacks and save lives every year."
The Rest of the Story
I have already outlined the reasons why I don't believe the Pueblo study provides adequate evidence to support a conclusion that the observed decline in heart attack admissions was attributable to the smoking ban in the first place.
However, for the purposes of this post, let's stipulate that the decline was attributable to the smoking ban. How is the American Heart Association able to conclude that the reduction in heart attacks was due to reduced secondhand smoke exposure, as opposed to an effect on the prevalence of intensity of active smoking among smokers?
The study collected no information on the smoking status of heart attack patients, no information on changes in levels of secondhand smoke, and no data on changes in smoking prevalence, smoking intensity, or cigarette consumption. Thus, it is impossible to draw any conclusions about whether the heart attack decline (if indeed due to the smoking ban) was attributable to reduced secondhand smoke exposure or reduced levels of active smoking.
If anything, the more plausible hypothesis would be that any reduction in heart attacks would be predominantly attributable to smoking cessation. After all, there is abundant evidence that smoking cessation can reduce heart attack risk dramatically, and in a relatively short time period. There is, however, no similar evidence regarding secondhand smoke.
Moreover, the mechanism that is being postulated as explaining the reduction in heart attacks due to secondhand smoke exposure (that secondhand smoke exposure, even for brief periods, can trigger heart attacks by interfering with endothelial function and increasing platelet activity) would hold equally well for active smoking (since active smoking also interferes with endothelial function and increases platelet activity).
The Heart Association's reasoning here makes no sense. I think one has to question why they are jumping to such a premature and unsupported conclusion. The only explanation I can think of is that they are so anxious to provide support to the push for smoking bans that they are jumping on the opportunity to link secondhand smoke exposure with people dropping dead on the spot from heart attacks. That type of evidence could convince reluctant policy makers to enact smoking bans.
While I support workplace smoking bans, I do not support the idea of relying upon shoddy science to promote such bans. And I certainly do not approve of the intentional manipulation of the public's understanding of the scientific issues regarding secondhand smoke in order to promote our cause.
Here, I think the conclusions being drawn are unsupported by the scientific evidence (even if one blindly accepts that the reduction in heart attacks in Pueblo was due to the smoking ban, a conclusion which I do not believe is reasonable in the first place).