What are e-cigarettes?

E-cigarettes are battery operated nicotine inhalers that consist of a rechargeable lithium battery, a cartridge called a cartomizer and an LED that lights up at the end when you puff on the e-cigarette to simulate the burn of a tobacco cigarette. The cartomizer is filled with an e-liquid that typically contains the chemical propylene glycol along with nicotine, flavoring and other additives.

The device works much like a miniature version of the smoke machines that operate behind rock bands. When you "vape" -- that's the term for puffing on an e-cig -- a heating element boils the e-liquid until it produces a vapor. A device creates the same amount of vapor no matter how hard you puff until the battery or e-liquid runs down.