The hope many 
smokers2 have of being able to enjoy their habit without 
restrictions3 might go up in smoke as the World Health 
Organisation4 (WHO) calls for a ban on e-cigarettes indoors. The organisation believes this alternative to conventional cigarettes might not be safe for secondary smokers, as e-cigarettes could increase the levels of some 
toxins5 and 
nicotine6 in the air.
	 
	E-cigarettes work by heating liquid nicotine - the substance in tobacco which makes it 
addictive7 - and turning it into vapour, which is breathed in by the 
smoker1. Since there's no smoke, 
puffing8 on e-cigarettes is being called 'vaping'.
	 
	According to estimates, the number of e-cigarette users in the UK alone has tripled over two years to more than 2 million, in a market worth more than £90m a year.
	 
	Many think e-cigarettes let smokers avoid legislation put in place about seven years ago to protect staff in the workplace. Vaping bars have sprung up in London, but their future 
remains9 uncertain. A growing concern about public health has led many pubs, train companies and offices to ban the use of these devices.
	 
	The British Medical Association is joining the WHO in asking for restrictions on e-cigarettes. They fear 
marketing10 them as fashion accessories or medical aids might 
undo11 their campaign against smoking. 
Ram12 Mooray from the organisation, said: "Our biggest concern is that smoking becomes 
glamorous13 again."
	 
	So, do the disadvantages of e-cigarettes 
outweigh14 the benefits? The debate is likely to heat up. Research by University College London says that for every million smokers who switch to e-cigarettes, more than 6,000 lives a year could be saved. Some smokers are using them to reduce their 
craving15 for cigarettes.
	 
	Professor Peter Hayek, Director of the Tobacco 
Dependence16 Research Unit at Queen Mary University of London, warns against restricting e-cigarettes. He says it's "like asking people to stop using mobile phones and tablets because of a one-in-10-million chance that the battery might overheat in your device."