About one-third of the largest U.S. cities are now covered by local comprehensive smoke-free laws and a similar number are covered by state smoke-free laws, according to the CDC.
Agency Director Thomas R. Frieden said Thursday that smoking bans "don't hurt business," and encouraged the remaining 20 largest U.S. cities to consider prohibitions that would cover bars, restaurants and workplaces.
"If we can protect workers and the public in the remaining 20 largest cities, 16 million people would be better protected from cancer and heart disease caused by secondhand smoke," Frieden said in a statement.
The review was published in the CDC's weekly Morbidity and Mortality Report.
The agency found that 10 of the 20 cities without smoking bans are in the South, and another 10 are in states where local smoking rules can be no stricter than state laws.