Hoboken, N.J. ? The fight over secondhand smoke is heating up anew.

One study, which is likely to be published in the next few days, is expected to show a decrease in health problems when workplaces in one Montana town went smoke-free.

And a major new study, released Tuesday, finds that more than half of U.S. food-service workers, the nation’s fourth-largest occupation, have no protection from cigarette smoke. The report, issued by the American Legacy Foundation, which promotes anti-smoking policies, found that in general blue-collar and service workers are lagging compared with white-collar employees. Rates of cancer and respiratory diseases are higher among blue-collar and service workers, and their medical expenses are considerably higher.

“We’re hoping this study will further accelerate a trend that is already accelerating, that is that more people are covered by smoke-free laws for their employment,” said Cheryl Healton, president of the Legacy Foundation, which is based in Washington.

So far, five states — California, Connecticut, Delaware, Maine, and New York — mandate that all places of employment be smoke-free. A Massachusetts law is waiting for the governor’s signature, and new legislation is moving through the Georgia statehouse. Florida, Idaho, and Utah include most restaurants and some bars in anti-smoking legislation. And scores of individual communities from Whitehorse, Alaska, to Lexington, Ky., are now smoke-free.

In Lawrence, Kan., the City Commission is expected to soon receive a draft ordinance that would ban smoking in the workplace, though the outcome of a vote on an outright ban is still up in the air.

The debate is likely to heat up even more in the next few days after the publication of a study of smoking in Helena, Mont. The study is expected to show that when the city’s workplaces went smoke-free, the heart-attack rate dropped in half. After a judge reversed the smoke-free move, the rate went back up.

The issue of banning smoking in restaurants and bars has been contentious for years. Restaurant associations often warn that patronage will drop if they can’t provide smoking sections. The industry has tried to convince lawmakers that ventilation can resolve the problem.

“A lot of studies have shown that secondhand smoke is 100 times worse in a household than a restaurant,” said Brad Dayspring, a spokesman for the National Restaurant Assn.