Research conducted by Public Health England shows that using e-cigarettes is 95% less harmful than smoking traditional tobacco cigarettes. 

In addition, numerous independent studies confirm that switching from traditional cigarettes to e-cigarettes significantly reduces exposure to toxic substances. However, experts emphasise that the safest option for health is still to avoid both smoking and vaping altogether.

Key Findings

• The report concludes that using e-cigarettes is around 95% less harmful than smoking conventional tobacco cigarettes (i.e., smoking combusted tobacco) as the best current estimate.
• Nearly half of the UK adult population (44.8%) did not realise that e-cigarettes are much less harmful than smoking at the time of the review. There was no evidence at that time that e-cigarette use among children or non-smokers routinely acted as a ‘gateway’ into smoking tobacco.
• The authors emphasise that e-cigarettes are not risk-free but, compared to smoking, “carry just a fraction of the harm”.
• The report also notes that e-cigarettes may help smokers to quit, especially when used alongside behavioural support from smoking cessation services.

Methodology & Context

• The review was commissioned by PHE and authored by researchers at King’s College London, Queen Mary University of London and others.  
• The document describes the e-cigarette market (devices, liquids), prevalence of use in Great Britain, patterns of switching from smoking to vaping, harm perceptions, nicotine delivery, toxicology and safety evidence.  
• The “95% less harmful” estimate is explained in an authors’ note: it is based on evidence that many of the harmful constituents of cigarette smoke are either absent in e-cigarette vapour or present at levels far below those in smoking, often <1% of the levels seen in cigarettes.  

Policy Implications

• PHE advises that e-cigarettes could offer a low-cost intervention to reduce smoking among more deprived groups (where smoking prevalence tends to be higher). 
• Local “stop smoking” services should engage with smokers who wish to use e-cigarettes and provide behavioural support alongside vaping to maximise quitting success.
• Health and social care professionals should provide accurate information about the relative risks of smoking vs. vaping — the misperception that vaping is as harmful as smoking could discourage switching.

Limitations & Cautions

• The estimate of “95% less harmful” is acknowledged by the authors as a best current estimate, not a precise measurement, and is contingent on evolving evidence. 
• The report recognises that long-term health effects of e-cigarette use are not well established, and that caution is needed, especially for never-smokers or young people. 
• Some critics have later argued that the foundation for the 95% figure was weak (for example, reliant on expert opinion and limited data).

Summary in a Nutshell

 According to this major PHE review, switching from smoking tobacco to using e-cigarettes could result in a very large reduction in harm (on the order of 95%) for a current smoker switching completely. But this does not mean vaping is totally safe. The context emphasises that quitting smoking entirely remains the best outcome.