Smoking kills nearly half a million Americans every year. Tobacco-less vaping products, like electronic cigarettes, have helped many people kick their deadly smoking habit. So why are they controversial?

One reason is a recent study that suggests smokers who use electronic cigarettes are less likely to quit smoking. The study has received considerable media attention and has emboldened public health activists to call on governments to clamp down on electronic cigarettes, making them harder to buy and use. That could spell disaster for public health.