Vaping: what we know and what we don’t about e-cigarettes

This article was originally published in April 2021, but was updated in November 2023 

It’s been a decade or so since e-cigarettes (commonly known as ‘vapes’) first gained popularity in the UK. Since then, the types of devices available and the number of people using them has risen sharply. 

And as the popularity of vaping has grown, so has the debate around it. It’s important to note that this information relates to legal e-cigarettes – this means vapes that are registered with the UK Medicines and Healthcare products regulatory authority (MHRA) and follow UK regulations. 

The big selling point for e-cigarettes is that they’re a way to help people stop smoking and reduce harm from the biggest cause of cancer in the world, tobacco. According to the Office for National Statistics, the level of smoking in the UK in 2022 was the lowest it had been since 2011. This follows the same trend as smoking rates in 2021, where it was suggested that the decrease could be partly due to the rise in vaping.  

But it’s a balancing act. Most e-cigarettes contain nicotine, which is the addictive chemical in tobacco. It’s important to make sure that people who have never smoked, particularly young people, don’t start to use them. 

While it may be hard to remember a time before vaping, in the grand scheme of research, there hasn’t been enough time yet to get the whole picture. And there’s still a lot more we need to understand about e-cigarettes. 

Linda Bauld, Professor of Public Health at the University of Edinburgh, says, “These are still relatively new products. But a huge amount of research has been done. It’s a far more sophisticated discussion now than it was in the early years.” 

Here are the big questions around e-cigarettes, what we know and what we still need to find out. 

Is vaping safe? 

There are a lot of mixed messages out there when it comes to e-cigarettes, with many headlines suggesting that vaping is just as bad or worse than smoking. 

In fact, research so far shows that vaping legal e-cigarettes is far less harmful than smoking. 

Some studies have shown harmful effects of e-cigarette vapour. However, these are usually conducted on animals or cells in the lab, rather than in people. And the concentrations of e-cigarette vapour used are often much higher than people would be exposed to in real life. 

Whilst these studies are useful to explore the potential effects of e-cigarettes, they shouldn’t be used to estimate real-world impact in humans. 

The tone of the debate may also depend on where you live. In 2019, the US saw an outbreak of several thousand cases of a respiratory illness called ‘EVALI’ (‘e-cigarette or vaping product use-associated lung injury’) and nearly 70 deaths linked to the use of vaping products. But again, headlines can be misleading, as the outbreak was actually caused by contaminants in illegal products and not to regular vaping. There was no similar outbreak in the UK, and the chemicals of concern are banned here. 

However, if you do vape, it is important to make sure that you buy your vaping products from a reputable source, as there has been a rise in illicit and unregulated vaping products being sold across the world.  

The best evidence available in humans shows e-cigarettes are far less harmful than smoking. For example, one study found significantly lower levels of exposure to harmful chemicals in people who switched from smoking to vaping compared with those who continued to smoke. These levels were similar to people using nicotine replacement therapy (NRT). There’s also no good evidence that second-hand e-cigarette vapour is harmful to bystanders. 

But e-cigarettes are a relatively new product. For this reason, there isn’t enough research yet into long-term use, or into their effects in people who have never smoked.  

“In people who vape, the vast majority are smokers or ex-smokers. So unpicking the relationship between those two risks is really tough” says Bauld. “Definitive answers about safety may still take many years to identify”. 

In short, there’s a lot more to learn. Cancer Research UK is funding research into e-cigarettes to help to answer some of the outstanding questions. 

But what researchers have had time to observe, over decades, is the huge amounts of research showing that tobacco is extremely harmful. Which is why experts can be confident that e-cigarettes are far less harmful than tobacco. This is broadly agreed by researchers and public health bodies. 

Do e-cigarettes help people to stop smoking? 

There’s growing evidence from around the world that e-cigarettes can help people stop smoking. In England, a study that looked at e-cigarette use and smoking cessation across the population estimated that e-cigarettes may have helped around an additional 50-70,000 people in England in 2017 to quit for the long term. 

Research shows the best way to stop smoking is through free support from stop smoking services. We now have evidence that e-cigarettes combined with support from stop smoking services are also effective in helping people to stop smoking.  

Bauld says that smoking is still the largest preventable cause of cancer and is linked to 15 different types. “Supporting smokers to quit and young people to not start is a really important cancer prevention priority. So, if e-cigarettes can provide support for individuals as an aid to smoking cessation, then that’s of interest to cancer researchers.” 

But there’s still a lot we need to find out. For example, we need to know more about the role that different types of devices, nicotine concentrations and flavours play in helping people to stop smoking. 

Although smoking rates in the UK continue to fall, levels in the most deprived populations are still much higher than in the least deprived, so experts are especially interested in whether e-cigarettes could help reduce this inequality. Recent research has suggested that people from lower socioeconomic groups might be more likely to use e-cigarettes, but it’s not yet clear whether this means e-cigarettes are improving smoking cessation rates in these communities.