NY Sun; October 10, 2002
By Jacob Sullum
When Mayor Michael Bloomberg first proposed that New York City ban smoking in all bars and restaurants, one of his aides made a revealing comment to The New York Times. "The mayor will push this for all the same reasons he pushed the cigarette tax," he said.
In approving an unprecedented 1,800 percent hike in the city’s cigarette tax, Bloomberg had emphasized that he wanted to deter smoking by making it prohibitively expensive. Likewise, the main point of his smoking ban is to make the habit less convenient and less socially acceptable, thereby encouraging smokers to quit.
Ostensibly, however, the ban is aimed at protecting bystanders, especially employees, from the hazards posed by secondhand smoke. Since that goal is more popular than the effort to protect smokers from themselves, the mayor can be expected to emphasize it when he testifies before the City Council in support of the ban today. In particular, he is likely to trot out a series of alarming factoids that exaggerate both the strength of the evidence against secondhand smoke and the level of risk suggested by the data.
For months the Department of Health has been running ads that warn, "Secondhand smoke kills." On the face of it, this claim seems plausible, since we know that the chemicals in tobacco smoke, absorbed in sufficient quantities, can cause deadly illnesses such as lung cancer and heart disease. But because the doses absorbed by nonsmoking bystanders are tiny compared to the doses absorbed by smokers, any risk would be correspondingly small and therefore difficult to measure.
That is one reason to be skeptical of precise-sounding numbers in warnings about secondhand smoke. The health department asserts, for example, that "secondhand smoke can increase your risk of getting lung cancer by 24%." This estimate comes from a 1997 analysis of 37 epidemiological studies comparing the lung cancer risk in people who lived with smokers to the lung cancer risk in people who did not.
Such studies typically find a weak, statistically insignificant association between living with a smoker and lung cancer. This is the pattern you’d expect if secondhand smoke had a barely detectable effect. It is also the pattern you’d expect if secondhand smoke had no effect, but other factors, such as dietary habits or unreported smoking by the subjects (all of whom are supposed to be lifelong nonsmokers), were boosting lung cancer rates among the spouses of smokers. Researchers try to take such factors into account, but since they are forced to rely largely on self-reports, it’s impossible to know whether their adjustments are adequate.
Another source of uncertainty is publication bias: Researchers are more inclined to submit, and journals are more likely to publish, studies that find an association between a suspected risk factor and a disease. Risk estimates based on published data therefore may be misleading.
These issues would not matter so much if the association between secondhand smoke and lung cancer were strong. But we are talking about a small increase in a very small risk. According to one epidemiologist’s estimate, living with a smoker raises a woman’s lifetime risk of lung cancer from about 0.34 percent to about 0.41 percent. By contrast, smoking is associated with a tenfold increase in lung cancer risk.
As University of Chicago biostatistician John C. Bailar told The Washington Post several years ago, the evidence that secondhand smoke causes lung cancer "is not as strong as some of the proponents say [it] is. That is not to say that they are wrong, but that they might be wrong."
The Environmental Protection Agency glossed over the problems with the evidence in its rush to declare secondhand smoke a "known human lung carcinogen." In 1998 that decision was overturned by a federal judge who concluded that the EPA had "publicly committed to a conclusion before research had begun" and "adjusted established procedure and scientific norms to validate the Agency’s public conclusion."
The evidence concerning secondhand smoke and heart disease—the basis for the New York City health department’s claim that "secondhand smoke kills more than 40,000 Americans each year"—is even more problematic. Bailar and other critics have noted that the risk increase attributed to secondhand smoke, around 25 percent, is implausibly high. It is about one-third the risk increase associated with smoking itself, which involves exposure levels perhaps 100 times as high.
One of the health department’s most startling claims is that "just 30 minutes of exposure to secondhand smoke can greatly increase your risk of heart attack." This assertion seems to be a distortion of a 2001 study that found reduced coronary flow velocity reserve, a measure of circulatory efficiency, in a group of Japanese men exposed to secondhand smoke for a half-hour. The study, which focused on acute effects, did not show any lasting changes, let alone the sort that would "greatly increase your risk of heart attack."
Whatever the hazard posed by secondhand smoke, of course, many people would like to avoid it, if only because it makes them uncomfortable. The question is whether this desire gives them a right to demand a smoke-free environment wherever they go, even on other people’s property. In a free society, there ought to be room for bars and restaurants that welcome smokers, staffed by employees who are willing to tolerate the smoke in exchange for higher pay, better tips, or otherwise superior working conditions. By ruling out such voluntary arrangements, Bloomberg is trying to forcibly impose his one best way on a city famous for its diversity.
Jacob Sullum, a senior editor at Reason magazine and a syndicated columnist, is the author of For Your Own Good: The Anti-Smoking Crusade and the Tyranny of Public Health (Free Press).