Following the lead of New York City Mayor Michael R. Bloomberg, Cambridge officials are considering a ban on smoking in some public spaces. Both Bloomberg and members of the Cambridge City Council cite health risks associated with secondhand smoke, but studies of the actual effects of outdoor smoke are scarce and their findings are limited. A ban on smoking in city parks, then, seems excessive. We urge the Council to abandon the proposal.

At the moment, Cambridge’s ban is in its infancy: The City Manager and the Public Health Department are still investigating the feasibility of enacting it, and a hearing on the issue will not take place until later this year. The Bloomberg plan on which it is based is likely to cover “parks, beaches, marinas, boardwalks and pedestrian plazas throughout the city,” and violators will probably have to pay fines on the order of $50. But it is not clear what the scope of a Cambridge version of the ban would be or how it would be enforced.

With specifics occupying the city’s attention, the actual justification for a policy change seems to have been rather rashly presupposed. Councilor Marjorie Decker, who proposed the measure and rallied the unanimous support of the City Council last week, insists that “anyone who is in a publicly funded space like a park should have a reasonable level of confidence that they are in a toxic-free zone.” This assumes that the smoking allowed under current policy creates dangerously toxic environments, which is unproven and probably untrue.

Of course, the adverse health effects of some forms of secondhand smoke should not be ignored. Smoke-filled indoor establishments bring undeniable harm to non-smoking patrons and workers alike, and we wholeheartedly support current prohibitions on smoking in the workplace. But what little evidence exists on the matter suggests that outdoor smoking generally exposes bystanders to dramatically lower toxin levels than indoor smoking.

One finding, occasionally quoted in favor of restricting outdoor smoking, comes from a 2007 controlled experiment by Stanford researchers. The Boston Herald has summarized that finding with the claim that “Within 2 feet, second-hand smoke exposure is just as bad outside as inside.” This is important information and might be relevant to any attempts to regulate crowded sidewalk cafes, but it hardly justifies the proposed ban. We rarely find ourselves within arm’s length of strangers in public parks for prolonged periods and could easily walk away if we did.

More relevant to this issue is the observation by one of the Stanford study’s authors that “When you go a little distance or stay upwind, the exposure [to toxins] goes way down.” The same researcher speculates that being surrounded by people smoking could produce significant ill effects. But here in Cambridge, parks are big enough and smokers few enough that such a scenario is unlikely even without the proposed ban.

We support the restrictions on smoking already in place throughout the state, and the City Council need not impose this additional one on residents. To do so would be not only paternalistic but also unnecessary. In this case, Cambridge would do well not to follow in the footsteps of New York City.