If you're looking to stop smoking for Stoptober, you may have considered using e-cigarettes as a quitting tool. Small battery-powered devices, which allow you to inhale nicotine through a vapour, they have become increasingly popular among smokers and ex-smokers alike. According to a survey by Action on Smoking and Health (ASH), around 2.9 million British adults used e-cigarettes in 2017.

Unlike cigarettes, which burn tobacco and produce a cocktail of harmful chemicals, e-cigarettes work by heating up a liquid nicotine solution. This means users are not exposed to carbon monoxide or tar, two of the deadliest components of tobacco smoke. The devices are billed as a safer way for smokers to manage their cravings.

However, there is a lot of confusion in the air about whether the marketing claims are true. Many news articles on the subject seem designed to inspire mistrust, while the e-cigarettes company JUUL has been hit with several lawsuits. According to one claimant, vaping left her teenage son "heavily addicted to nicotine ... anxious, highly irritable and prone to angry outbursts".

Perhaps as a result, public opinion remains split down the middle. In the ASH survey, only 13% of respondents said they thought vaping was a lot less harmful than smoking, while 26% thought it was equally bad or even more so.

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They're 95% less harmful than cigarettes

It may come as a surprise, then, that the evidence in its favour is relatively clear-cut. As Dr Sarah Jarvis, clinical director of Patient.info, explains, these devices are not completely harmless. However, they carry only a small fraction of the health risks of cigarettes.

"The liquid and vapour contain some potentially harmful chemicals also found in cigarette smoke, but at much lower levels," she says. "Based on an assessment of the available international peer-reviewed evidence, Public Health England and the Royal College of Physicians estimate that they are at least 95% less harmful than cigarettes. We need to keep monitoring the evidence closely for any longer-term health impacts that might emerge. However, it's clear that for a smoker, switching completely to an e-cigarette is a far safer option than continuing to smoke."

Professor Ann McNeill, a professor of tobacco addiction at Kings College London and a tobacco policy expert, says she is very much in favour of e-cigarettes as a way to stop smoking.

"What I care about is health, and in my view what we need to be saying to smokers is to stop smoking as soon as possible," she says. "If to do that you need or prefer to continue to use nicotine, that's OK with me."

As she explains, the health concerns associated with vaping are far eclipsed by the dangers of smoking, which she calls 'uniquely deadly'.

"I would encourage any smoker who hasn't tried these products to try them as a means of stopping," she says. "The critical thing is to try to stop smoking as soon as possible. You don't want to use an e-cigarette and also smoke - you want to move away from smoking as quickly as you can, and if you need to carry on using e-cigarettes for a while after you've quit that's fine."

Why the controversy?

So why are e-cigarettes so often presented as dangerous, if they're such an effective cessation tool? Professor McNeill thinks it comes down to three factors: a long-standing emphasis in national guidance on total abstinence from nicotine; distrust of e-cigarette manufacturers; and uncertainty about the long-term health effects.

Regarding the first of these, this applies equally to other smoking cessation tools (eg, nicotine patches and tablets). Arguably, the concern is misguided - although nicotine does have some health risks, it is far less harmful than smoking. One large study showed that nicotine replacement therapies increase the rate of quitting by 50-70%. And the most recent guidance on smoking from the National Institute for Health and Care Excellence (NICE) was fundamentally different from their previous guidance on 'Smoking cessation'. Entitled Smoking: harm reduction, it included guidance for people who 'may want to stop smoking, without necessarily giving up nicotine', as well as for those who want to quit completely.

The second concern is an upshot of big tobacco companies having moved into e-cigarette production.

"For a while, it was the independent cottage industries that were developing these products, but now the tobacco industry is moving into this field," she says. "That worries people who have always seen the tobacco industry as the enemy - how can it be part of the solution? I'd prefer to see e-cigarettes produced independently, but it's better for somebody to be using one of these products than smoking, whoever's producing it."

As for the long-term health effects - well, evidently there's only so much we can say about a product first marketed in 2004. However, we do have more information about their risk profile than many people realise.

"There is broad consensus across leading UK health and public health organisations, including the RCGP, BMA and Cancer Research UK, that e-cigarettes are far less harmful than cigarettes. This is also the conclusion of three major US health reports published this year," points out Jarvis.

Using them to quit smoking

Some people have also made the argument that e-cigarettes are a kind of gateway drug. As the argument goes, young people will try vaping and ultimately move on to smoking. On top of that, there has been concern generally about the use of e-cigarettes among teens. (Nicotine is considered unsafe for young people.)

In the US, much of the backlash against vaping has been for precisely this reason. E-cigarette use rose by 900% among US high school students between 2011 and 2015, with over 2 million teenagers having tried e-cigarettes by 2016. In 2016, the FDA started to enforce rules about the sales and marketing of these products, with a view to bringing the situation under control. For example, they can no longer be purchased by under-18s.

In the UK, use among teens is much rarer. In 2016, less than 1% of 'never smoker' children regularly used e-cigarettes.

"So far, the evidence tells us that regular use of e-cigarettes by young people in the UK is rare and almost entirely among those who have already smoked, while smoking rates among young people continue to decline," says Jarvis.

However, she agrees with McNeill, who thinks we need more research around the marketing and regulatory side of these products.

"The biggest challenge is how you balance the risks of attracting young people to the products, while encouraging smokers to try them," says McNeill. "Getting that balance right is difficult. So far so good in England - we seem not be seeing widespread uptake of the products but we are seeing smokers using them to stop."

As Jarvis explains, many smokers find it hard to quit using willpower alone, meaning e-cigarettes (or other nicotine replacement therapy products) combined with expert support can make a genuine difference.

"This year, Stoptober has developed a free online Personal Quit Plan which helps smokers find a combination of stop smoking support that's right for them based on their level of tobacco dependency and any quitting support used previously," she says. "If you are a smoker, quitting is the best thing you can do for your health and you don’t need to go it alone. I really want to encourage all smokers to search 'Stoptober' and use the Personal Quit Plan to find support that's right for them."