If you hang out in bars, clubs, restaurants or other open public spaces, you will likely see someone “vaping” -- inhaling on an electronic cigarette and exhaling water vapor. It is a $3 billion a year industry in the U.S. Imagine, being able to light up anywhere and get your nicotine fix from a “cigarette,” orange tip glowing brightly as you inhale. For most users, it’s the real thing.

So far, e-cigarettes have been found to be safer than regular tobacco-filled cigarettes. Smoke, the biggest danger from tobacco use, isn’t produced by e-cigarettes. Levels of dangerous chemicals found in e-cigarette vapor are a fraction than that found in traditional tobacco products.

"E-cigarettes may be less harmful than cigarettes," says M. Brad Drummond, MD. "But we still don't know enough about their long-term risks or the effects of secondhand exposure." Drummond is an assistant professor of medicine at Johns Hopkins University School of Medicine.

The Chinese created the first electronic cigarette, and it was introduced to local markets in 2004. They were then exported to major markets, with e-cigs hitting the U.S. market in 2007. Manufacturers say that e-cigs are alternatives to smoking tobacco products such as cigarettes, cigars and pipes. E-cigs are on track to outsell tobacco products by the end of the decade.

What is an electronic cigarette and how does it work?

E-cigs have detachable mouthpieces or cartridges that contain absorbent material to hold the liquid nicotine and flavorings. There is an atomizer inside the long tube, which attaches to the mouthpiece. That atomizer is a heating unit that turns the nicotine and various flavorings to water vapor, which the user then inhales and exhales. A lithium ion battery usually runs the whole deal, and you can find e-cigarettes in rechargeable set-ups. The newer versions of e-cigs contain a sensor that heats the elements as soon as you draw on the cigarette. Older versions have a button you press that will heat the element to vaporize the nicotine.