But now the future of electronic cigarettes is coming under increasing threat after ScotRail and Abertay University became the latest major organisations to outlaw their use on their property.
They join a string of other leisure, education and healthcare establishments – including cafe chain Starbucks, pub operator Wetherspoons and travel firms such as Lothian Buses, EasyJet and Jet2 – to ban the use of the product.
E-cigarettes mimic the effect of cigarettes through a nicotine hit but produce a steam vapour rather than smoke.
The latest bans come just days after the Medicines and Healthcare Products Regulatory Agency said it would require
e-cigarettes to be licensed as medicines from 2016.
The organisations behind the bans cite health reasons or the belief that customers appearing to light up may encourage others to flaunt the smoking ban with real tobacco products.
And union leaders have called for the use of the device to be stopped in all workplaces –claiming that the practice could prevent smokers from giving up.
Some companies, such as Wetherspoons, claim they have found e-cigarettes too difficult to monitor, creating a loophole for customers trying to pass real cigarettes off as electronic ones.
A number of supermarkets, including Sainsbury and Morrisons, have also outlawed the practice, while many major shopping centres including Intu Braehead in Glasgow also ask customers to refrain from using the product.
“No-one should be using e-cigarettes at work in an attempt to get round the smoking ban,” said TUC general secretary
She added: “The danger is that many smokers will simply use e-cigarettes in addition to their usual tobacco ones, rather than instead of them.”
ScotRail said it has banned passengers from using the devices on its trains, on platforms and at depots amid concerns that the use of e-cigarettes may lead other people to believe that they could smoke real cigarettes on board.
A spokeswoman for ScotRail said: “We are aware that there are still many unanswered questions regarding the efficacy and safety [of e-cigarettes].
“We are also concerned that their realistic appearance could prompt tobacco smokers to think it is OK to light up, which could lead to misunderstandings.
“If, in future, new information comes to light about the efficacy and health implications of e-cigarettes, we will be happy to review this arrangement.”
Meanwhile, Abertay University announced that it will punish students and staff caught using e-cigarettes on its campus with the same penalty as those found smoking tobacco.
A spokesman said: “Recent changes to our smoking policy with regards to e-cigarettes have been made following the views of the British Medical Association and the World Health Organisation. Both of these organisations say there is not enough evidence either way to determine if e-cigarettes are better for your health or not. With that in mind, we thought it better to err on the side of caution.”
Last week, 13 of Scotland’s public health directors called for the products to be classed as equivalent to conventional cigarettes.
But proponents of e-cigarettes claim they provide users with the nicotine and vapours associated with tobacco, but without many of the other health risks..
And the anti-smoking lobby group Ash Scotland said it did not support a widespread ban on the product – claiming that they could “play a role” in helping smokers to quit.