At the urging of a regional coalition of public health experts and community members, the city of Cambridge is considering a proposal to ban all smoking inside local bars and restaurants.

More than 50 people—almost all of them supporters of a smoking prohibition—attended a City Council ordinance committee meeting Wednesday to discuss the idea.

“We know that second-hand smoke is a Class A carcinogen,” said John G. O’Brien ’72, chief executive officer of the Cambridge Health Alliance. “All workers need to be protected from hazardous exposure to second-hand smoke.”

While smoking has been prohibited in most Cambridge work sites for the last three years, an exception currently exists for bars and restaurants.

“Bars and restaurants are work sites,” said Sara E. Reese of the Cambridge Public Health Department. “Sometimes people forget that.”

Similar public hearings are occurring in other towns in the Boston area. Clean Air Works, the regional movement to ban smoking in area restaurants, is a coalition of local boards of health, non-profit health organizations, labor unions and workers.

Prohibitions on smoking in restaurants are already in effect in the nearby towns of Arlington, Belmont, Lexington and Medford, as well as on all of Martha’s Vineyard and Nantucket and in several towns on Cape Cod.

The main argument against local bans on smoking in restaurants and bars is that it would hurt small businesses by causing customers to go to others towns that permit smoking.

But proponents of the bans said the regional approach would remove any incentive for customers to bring their business to restaurants in neighboring towns.

“If the whole region goes at one time, that economic argument is completely dead,” Reese said.

Local prohibitions on smoking would also be more effective than a state-wide ban, because state action would be more open to legal challenges by tobacco companies that would lead to a “watered down” measure, said Howard K. Koh, commissioner of the Mass. Department of Public Health.

Spokespersons for the mayors of Boston, Somerville and Brookline testified before the committee, saying that they supported the Cambridge amendments as well as similar measures in their own cities.

—Staff writer Stephanie M. Skier can be reached at skier@fas.harvard.edu.