The Centers for Disease Control and Prevention study found 19.6 percent of working adults smoke, but as many as 30 percent in the mining, construction and food service industries smoke. Librarians and teachers smoked the least, at less than 9 percent.
Also, people who work outdoors are less likely to face indoor smoking bans seen in other workplaces.
The study is based on in-person interviews of more than 113,000 working adults in the years 2004 through 2010.
Click here to read the CDC report online