E-cigarettes aren't yet federally regulated as tobacco products, but many cities and some states are already moving to include the devices in their smoking bans. Such bans are raising a debate about whether e-cigarettes should be permitted to be used in smoke-free workplaces.

Gary Nolan was a two-pack-a-day cigarette smoker until he switched to e-cigs. Now Nolan, who hosts a libertarian talk show based in Columbia, Mo., freely puffs — or vapes, as it's come to be called — at work.

Electronic cigarette makers are getting bold with their advertising, using provocative new print ads and celebrity endorsements on TV. But public health advocates say these images are luring kids to hook them on nicotine.