This is the latest come-on from the busybodies who want to banish smoking from private businesses. The claim, which has been credulously repeated by the news media, is based on a study of heart attacks in Helena, Montana, during the six months after a smoking ban took effect.

The unpublished study is the work of Richard Sargent and Robert Shepard, two local physicians who were leading advocates of Helena's smoking ban, and Stanton Glantz, a well-known anti-smoking activist who directs the University of California at San Francisco's Center for Tobacco Control Research and Education. Sargent says they discovered that the smoking ban "led to an immediate and dramatic decline in the number of heart attacks experienced in Helena."

In truth, the study shows nothing of the kind. The fact that Sargent and his fellow tobaccophobes got away with this kind of prevarication shows how eager journalists are to accept any factoid that helps the anti-smoking cause.

According to data Sargent presented at a recent meeting of the American Academy of Cardiology, St. Peters Community Hospital in Helena saw an average of less than four heart attacks a month from June, when the smoking ban took effect, until December, when the ordinance was suspended because of a legal challenge. From 1998 through 2001, by contrast, the hospital recorded an average of about seven heart attacks a month during the same part of the year.

In a UCSF press release, Glantz declared, "This striking finding suggests that protecting people from the toxins in secondhand smoke not only makes life more pleasant; it immediately starts saving lives."

To a more skeptical eye, this striking finding suggests the perils of drawing conclusions from a single study involving tiny, volatile numbers. As Richard Pasternak, an associate professor of medicine at Harvard, told UPI, "This is a small study, so we have to be cautious in how we interpret these results."

Unless we work for the news service at Glantz's university. The headline on the UCSF press release, which was echoed by news outlets, announced, "Public Smoking Ban Slashes Heart Attack Rate in Community."

A little calculation shows how preposterous this claim is, even if you believe that secondhand smoke causes heart disease. The American Heart Association attributes 35,000 heart disease deaths a year, about 5 percent of the total, to secondhand smoke.

It seems reasonable to assume that the proportion would be similar for heart attacks, fatal or not. So even if a city completely eliminated secondhand smoke (which Helena's ban did not do, since it did not apply to smoking at home), how could that possibly cut heart attacks in half?

Sargent and Glantz note that smoking bans also encourage smokers to cut back or quit. Inconveniently for them, that point suggests that any drop in heart attacks could be due to less smoking rather than less exposure to secondhand smoke.

In any case, the numbers still don't add up. According to the U.S. Centers for Disease Control and Prevention, smoking accounts for about one-fifth of heart disease deaths. So even if every smoker in Helena quit (which no one claims happened), you would not get anything like the drop that Sargent, Shepard and Glantz attribute to the ban.

If smoking bans cut heart attacks in half, it's odd that no one has noticed it before, especially in big cities such as Los Angeles and San Francisco, where an effect of such magnitude should have been obvious. Indeed, why didn't Glantz study hospital data in places within his own state where the samples would have been much bigger and the results more meaningful, instead of focusing on what Sargent calls "a tiny little community in the middle of nowhere"?

California's ban on smoking in workplaces took effect in 1995; it was extended to bars in 1998. Yet according to CDC data, the number of heart disease deaths in California did not drop substantially in either year. If smoking bans cut heart attacks in half, surely the effect would have shown up in these numbers.

Likewise, Delaware should see a sharp drop in heart attacks now that it has banned smoking in all workplaces. So should New York City, where a smoking ban took effect this month, and New York state, which recently passed a ban that takes effect in July. Ditto Boston, Chicago, Dallas and Florida. Or is there something special about hearts in Helena?