During Prohibition, making and selling liquor was illegal, but drinking it was not. With tobacco, we are moving toward the opposite situation, where it will be legal to make and sell cigarettes but not to smoke them.

A smoking ban recently approved by the city council of Belmont, Calif., a town halfway between San Jose and San Francisco, is so sweeping that saying where it does not apply is easier than saying where it does. Smoking will still be allowed in tobacco shops, in automobiles, in some hotel rooms, in private residences that do not share a floor or ceiling with other private residences, and on streets and sidewalks, assuming you can find a spot that is not within 20 feet of a smoke-free location.

That may be hard, since Belmont's smoke-free areas include not only buildings open to the public but outdoor locations where people wait, such as ATM lines and bus stops, or work, such as construction sites and restaurant patios. But a smoker who despairs of finding an outdoor area where smoking is allowed can still light up even if he does not own a car and is unlucky enough to live in an apartment or condominium. He just has to land a role in a theatrical production "where smoking is an integral part of the story."

Meanwhile, the Los Angeles suburb that dubbed itself "Clean Air Calabasas" when it was leading the smoke-free march into the great outdoors is considering an extension of its ordinance that would cover apartments. Even if your landlord doesn't care whether you smoke, Clean Air Calabasas does.

The official justification for these ever-more-intrusive smoking bans is that the slightest whiff of secondhand smoke poses an intolerable hazard. The Belmont ordinance claims tobacco smoke is "extremely dangerous," regardless of dose, and warns that even "exposure to outdoor secondhand smoke may present a hazard under certain conditions of wind and smoker proximity."

Predictably, the ordinance cites former Surgeon General Richard Carmona's assertion that "there is no risk-free level of secondhand smoke exposure." But this pseudoscientific leap of faith amounts to saying that every little bit hurts, even if the damage can't be measured.

Epidemiological studies generally find that adults who live with smokers for decades are slightly more likely to get lung cancer and heart disease. The difference is so small that it's hard to say whether it signifies a causal relationship. There is also evidence that very young children of smokers are more prone to earaches and lower respiratory infections. Continued...