Buddy, Can I Bum a Vape?

Once a novelty item, the electronic cigarette—a device that enables users to directly inhale vaporized nicotine—has now entered the mainstream. This year, 2.5 million Americans will spend an estimated $1 billion on e-cigs, double what they spent last year. Yet their rising sales have sparked concern over their safety. Enthusiasts say that e-cigs will sa…