According to Public Health England, there are now more than 1.3 million regular e-cigarette users in the UK. That’s an astonishing figure, given that, just five short years ago, anyone seen puffing away on one of these devices was treated like some kind of time-travelling space-drug-junkie from the year 2148.

The explosion in popularity of e-cigs and vaping has coincided with a steep, steady decline in the number of people smoking – just 19.3% of UK adults now smoke, the lowest percentage in 80 years – and a huge rise in people making fitness a central part of their lives: today’s 20-to-30-year-olds are three times more likely to regularly hit the gym than their counterparts 30 years ago, for example.

So there are a sizeable number of people out there who’ve kicked nicotine with the help of new-fangled e-cigarettes, and are generally looking after themselves better in terms of exercise.

But is it possible to be a ‘vaper’ and a self-improving fitness fan? We have no idea, which is why we spoke to University College London’s Professor Robert West – a leading expert on tobacco and e-cigarettes to see if e-cigarettes and fitness are mutually exclusive.

Hi, Professor West. To what do you credit the huge surge in vaping’s popularity? 

“Well, some people are using e-cigarettes in addition to smoking traditional cigarettes, but many are using them to get themselves off tobacco.

“Figures show that around 20,000 people in the UK have switched from smoking tobacco to smoking e-cigarettes in the last year alone – which means that around 10,000 lives have likely been saved by them.”

There’s got to be a downside though, right?  

“Well, we are at a risk of losing sight of proven methods of giving up smoking, such as the NHS Stop Smoking Service. With e-cigarettes, you’re 50% more likely to be able to give up tobacco [than by simply going cold turkey]. But with the NHS Stop Smoking programme, you’re 300% more likely.

“In my view, e-cigarettes do have a role to play in getting people off tobacco. If I was a smoker and I needed to stop – and they all do! – then I’d be using any means at my disposal.”

So what’s the key difference between vaping and fag-smoking?

“The crucial difference is that with vaping, you’re not taking in tar, as you are with cigarettes. Nicotine is what keeps you addicted to cigarettes, but the tar is what kills you. So when you’re vaping rather than smoking, you’re not taking in those literally hundreds of dangerous carcinogens.

Nicotine is what keeps you addicted to cigarettes, but the tar is what kills you

“That said, inhaling anything that’s not supposed to be in your lungs is going to cause you damage. But on a scale of zero to 100, if zero is breathing in fresh sea air, and 100 is smoking a cigarette, vaping is around five.

“Yes, it would. Firstly, the lungs would clear up considerably due to the lack of tar.

“Secondly, when you’re a smoker, one in 20 of your blood cells are tied up with carrying carbon monoxide, rather than oxygen. Within just one day of stopping smoking, all these blood cells will clear up and return to carrying oxygen – which is going to make you better at performing exercise.”

“Well, only a foolish pulmonologist [a doctor specialising in the respiratory tract] would say that’d never happen – but we can say with some confidence that that’s extremely unlikely.

“The key ingredient used in e-cigarette liquid is propylene glycol – ‘stage smoke’, essentially – and it’s already been extensively tested on both animals and people. So no, that ‘time bomb’ scenario is unlikely to come to pass.”