Death clock: secondhand smoke hype.

• Author: Sullum, Jacob
• Position: Secondhand smoke increases the risk of heart disease, research

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...