More than half of the UK's electronic-cigarette users have since given up smoking tobacco, according to a new report from Action on Smoking and Health (ASH).

The study, conducted by YouGov on behalf of ASH, shows an estimated 2.9 million adults in Great Britain currently use electronic cigarettes.

For the first time ever, the survey finds more ex-smokers (1.5 million) who use e-cigarettes than current smokers and the main reason people offered for their use of e-cigarettes was to stop smoking. While this is positive, there are still many people who “dual-use” combustible and electronic cigarettes which still exposes them to the toxic, cancer causing substances in tobacco smoke.

Professor Ann McNeill, Professor of Tobacco Addiction at King’s College London, said: “This year’s ASH survey finds that around 1.5 million vapers are ex-smokers, for the first time a larger number than those who continue to smoke.

"This is encouraging news as we know that vapers who continue to smoke continue to be exposed to cancer-causing substances. The message for the 1.3 million vapers who still smoke is that they need to go further and switch completely.”

There has been a four-fold increase in the number of vapers since 2012 when the figure was 700,000. However, growth has slowed a great deal in the last couple of years and fewer smokers year on year understand the reduced risk of vaping compared to smoking tobacco.

Deborah Arnott, chief executive of ASH, said: “It’s excellent news that the number of vapers who have quit smoking is continuing to grow, but there are still 9 million smokers compared to only 1.5 million vapers who don’t smoke at all.”

She went on to say: “The rapid growth in e-cigarette use has come to an end while over a third of smokers have still never tried e-cigarettes, saying the main reasons are concerns about the safety and addictiveness of e-cigarettes. It’s very important smokers realise that vaping is much, much less harmful than smoking.”