I HAVE never been a smoker, so as I sit at the bar, chin resting on one hand, I try to remember how Audrey Hepburn did it. I take a gentle drag and exhale. A white mist wafts around my face as I wait for the rush of nicotine hitting my brain. People start to stare. Then the inevitable happens: “Hey, you can’t smoke that in here.” Only in this case I can, because I’m not really smoking.

I’ve just “lit up” an e-cigarette, a battery-powered electronic device that I bought for $60 from a UK website. It looks just like a real cigarette – the tip even glows red – and with every drag a few micrograms of nicotine from a disposable cartridge (I got six with my purchase) should reach my lungs. My e-cigarette even produces puffs of “smoke”, but it isn’t burning, and so it’s not banned. I’m not the only one smoking these sticks. In the growing number of public places worldwide where smoking has been banned, a new breed of smoker has appeared puffing on similar gadgets.

The e-cigarette is not burning anything and so doesn’t produce any of the toxic products of combustion

E-cigarettes may help smokers evade the ban, but do they also help them evade the health consequences of smoking or give the habit up altogether? In September 2008 the World Health Organization issued a statement warning smokers that there was no evidence to back up claims that e-cigarettes could help them quit. So what do we know about them and is there any evidence that inhaling the chemicals they contain may be harmful …