E-cigarettes are almost completely free of health risks, and could save millions of lives, agreed health experts at a London summit to discuss the effects of the device.

E-cigarettes – which work by users inhaling vaporized nicotine – have enjoyed a surge of popularity since they were introduced around the turn of the decade, with around 7 million users in Europe. Nations have moved to crack down, but a growing movement claims they offer more benefits than risks.

“We can recommend that smokers who cannot quit should switch to e-cigarettes,” said leading researcher Dr. Konstantinos Farsalinos of the University Hospital Gathuisberg, Belgium. The risks were less than 1/1000th of smoking tobacco, he told Metro.

Dr. Farsalinos added that the devices were the most effective tools to quit smoking. “The best alternative before was around 20% [...] In my research up to 80% of participants using e-cigarettes have quit.” Medical journal The Lancet also found that e-cigarettes were more effective than Nicorette gum and patches.

The World Health Organization (WHO) estimates 1 billion people will die prematurely from cigarette use in the next century, and previous opponents of e-cigarettes are becoming more supportive. “It’s always better to quit nicotine use completely,” said Deborah Arnott, Chief Executive of UK health charity Action on Smoking and Health. “But it’s the smoke that kills you - not the nicotine - so for smokers who are heavily addicted switching to safer sources of nicotine could literally be a lifesaver.”

Debate rages over regulation, but e-cigarette advocates won a major battle as the European Parliament has abandoned plans to impose medical regulation that would restrict sales to pharmacies. “Regulation puts the businesses under threat, which could mean users are forced to smoke regular cigarettes again,” says Nigel Hislop of advocacy group Saveecigs.com.

Arnott expects regulation to cover advertising to ensure the devices do not become a “gateway to smoking” for children. Research efforts will focus on toxicity of refills to ensure safe levels, which the WHO cites in a warning to potential users.

But with projected users set to outnumber regular smokers in several European nations by 2016, lawmakers will have a difficult job to turn the tide. “It’s a consumer revolution, led by word of mouth rather than advertising,” says Chris Snowdon, a fellow at the Institute of Economic Affairs, a British think tank. “As exponential growth continues, so many people will be ‘vaping’ it will make the decision for politicians.”