Atlanta – A majority of America’s 50 largest cities are now covered by comprehensive smoke-free laws, better protecting workers from the risks of cancer and heart disease caused by secondhand smoke, according to a report from the Centers for Disease Control and Prevention.

As of Oct. 5, 30 of the largest 50 U.S. cities were covered by laws prohibiting smoking in all indoor workplaces, restaurants and bars, the report stated. These local and state laws cover nearly half of all Americans, a sharp increase from only 3 percent being covered in 2000, CDC said.

“If we continue to progress as we have since 2000, all Americans could be protected from secondhand smoke exposure in workplaces and public places by 2020,” Tim McAfee, director of CDC’s Office on Smoking and Health, said in a press release.

The study was published Nov. 16 in CDC’s Morbidity and Mortality Weekly Report.