Last summer, in a press release that accompanied his report on secondhand smoke, Surgeon General Richard Carmona claimed "even brief exposure to secondhand smoke" adversely affects the cardiovascular system and increases the risk of heart disease. How brief? Supporters of smoking bans have been competing to answer that question, with each claim less plausible than the last.
Michael Siegel, a physician and a professor at the Boston University School of Public Health, has been tracking the claims on his blog (tobaccoanalysis.blogspot.com). In November 2005, Siegel faulted the Campaign for Tobacco-Free Kids for asserting that "as little as 30 minutes of exposure to secondhand smoke can trigger harmful cardiovascular changes, such as increased blood clotting, that increase the risk of a heart attack." The following April, Siegel counted 65 anti-smoking groups that were attributing various adverse cardiovascular consequences, included hardening of the arteries and heart attacks, to a half-hour of second-hand smoke.
One of those groups, SmokeFree Ohio, was also claiming that merely 20 minutes of exposure causes a nonsmoker's platelets to become "as sticky as a smoker's," increasing the chance of a heart attack. Not to be outdone, SmokeFree Wisconsin began warning that after five minutes of exposure, "your body starts closing off arteries." In October the Minnesota Association for Nonsmokers declared that "just thirty seconds of exposure to secondhand smoke can make coronary artery function of non-smokers indistinguishable from [that of] smokers."
As Siegel notes, neither Carmona's report nor the "fact sheets" produced by anti-smoking groups offer evidence to support such claims. Since cardiovascular disease takes many years to develop in smokers, who absorb much larger amounts of the chemicals generated by tobacco combustion than bystanders do, the activists' accounts suggest that cigarette smoke defies the rules of toxicology, becoming more potent as the dose becomes smaller. Imagine what zero seconds of exposure could do.