Electronic cigarette (e-cig) usage has tripled over the past two years from 700,000 users in 2012 to 2.1 million in 2014.

A YouGov survey, commissioned by ASH, found that nearly two-thirds of e-cig users are current smokers and one-third are ex-smokers, an increase in the proportion of ex-smokers compared to previous years.

There has also been a consistent rise in the number of current and ex-smokers who use e-cigs on a regular basis from 2.7% in 2010 to 17.7% in 2014.

For the first time, the ASH YouGov survey also asked about the type of e-cigs used.

While the majority of e-cig users start off using rechargeable products with pre-filled cartridges, they soon move onto rechargeable products with separate tanks or reservoirs.

Among current users 47% most often using rechargeable e-cigs with pre-filled cartridges and 41% use rechargeable devices with a separate tank. 

The research also suggests that smokers are increasingly turning to e-cigs to help them cut down or quit smoking, while usage among non-smokers is negligible.  

Just under 50% of current smokers who also use e-cigs say they do so to help reduce the amount of tobacco they smoke, but not stop completely, while 37% use e-cigs “to save money compared with smoking tobacco” while 36% say they are using them to help stop smoking entirely.

The findings were published on the same day that the Advertising Standards Agency’s (ASA’s) consultation on the advertising of electronic cigarettes closed.

Launched at the beginning of March the consultation sought to “address public concern and uncertainty amongst advertisers” about how e-cigs should be marketed.

Among other things, it asked it asked if adverts showing under 25s using e-cigs should be banned.

ASH chief executive Deborah Arnott welcomed the report’s findings.

“The dramatic rise in use of e-cigs over the past four years suggests that while it is important to control the advertising of e-cigs to make sure children and non-smokers are not being targeted, there is no evidence that e-cigs are acting as a gateway into smoking,” she added.