Smoke-Free cigarretes

 I remembered about PM two days ago. They saw:

Headquartered in Stamford, Connecticut and listed on the New York Stock Exchange (NYSE: PM), at PMI, we are building our future on replacing cigarettes with smoke-free products that—while not risk-free—are a better alternative than cigarette smoking. 

I have used electro cigarette by four components: propylene glycol, glycerol, nicotine, flavors. And ... water? But I know if possible to use kkal measuring for anithing, it will burn!

Water don't burn! Zero kkal in the clear water!

It's say that elecro-sigarette with liquid include smoke too, but this amount is real less than in the traditional cigarettes. They are writing right, it has include 500 years experience. Oh, impossible to take better now =/

Maybe water vapor with nicotine will work or not ... Temperature must be around 20 degrees.

Why is propylene glycol and glycerol needed? How to does it work? What may replace it ... ?