Vaping vs. Smoking: What the Research Says

The short answer: yes, e-cigarettes are substantially less harmful than tobacco cigarettes - but they are not harmless.

Cigarette smoke is harmful primarily because of the thousands of toxic and carcinogenic chemicals produced by burning tobacco. E-cigarettes heat a liquid (containing nicotine, propylene glycol, vegetable glycerine, and flavourings) to produce a vapour - a process that does not involve combustion and does not produce the same range of toxic chemicals.

The NHS states that e-cigarettes are "around 95% less harmful than cigarettes" - a figure derived from a 2015 Public Health England review. However, this figure is an estimate, not a precise measurement, and reflects our best current understanding rather than a definitive long-term assessment.

Key known risks of vaping include:

• Nicotine dependence: Most e-cigarettes contain nicotine and therefore maintain addiction. Switching from smoking to vaping does not free you from nicotine dependence.
• Lung irritation: The vapour from e-cigarettes can irritate the airways, causing coughing and breathlessness, particularly with high-powered devices or certain flavourings.
• Cardiovascular effects: Nicotine from vaping, like from cigarettes, affects heart rate and blood pressure.
• Potentially harmful chemicals: Some e-liquid flavourings (particularly diacetyl, associated with "popcorn lung" in industrial settings) and degradation products of heating coils can produce harmful compounds, though typically at much lower levels than in cigarette smoke.

One of the most important cautions about vaping is that the long-term health effects are not yet fully known. E-cigarettes have only been in widespread use since the early 2010s - far too short a period to assess the effects of 20 or 30 years of vaping, which is the relevant comparison for smokers who start young.

The CDC explicitly states that e-cigarettes are not safe, and that youth, young adults, pregnant women, and adults who do not currently use tobacco products should not use e-cigarettes.

The WHO position is more cautious than the NHS: the WHO has not endorsed e-cigarettes as cessation aids and notes that the evidence on their effectiveness and safety is insufficient to make firm recommendations. The WHO is particularly concerned about marketing to young people and the potential for e-cigarettes to serve as a gateway to conventional smoking among youth.

Specific uncertainties include:

• Long-term respiratory effects of inhaling propylene glycol and vegetable glycerine aerosols
• Potential cumulative effects of flavouring compounds
• The health effects of metals released from heating coils (nickel, tin, lead)
• The relationship between vaping and lung disease (including EVALI - e-cigarette or vaping product use-associated lung injury, associated primarily with vitamin E acetate in illicit THC cartridges)

The regulatory position on e-cigarettes as a cessation tool varies significantly between countries:

• UK (NHS/MHRA): The NHS considers e-cigarettes as a potentially useful tool for adult smokers trying to quit, and NHS Stop Smoking Services can support smokers who choose to use e-cigarettes as part of their quit attempt. The NHS emphasises that the goal should be complete switching from cigarettes to e-cigarettes as a transitional step, then working towards stopping vaping as well.
• US (FDA): The US Food and Drug Administration has not approved e-cigarettes as a cessation aid. No e-cigarette has been granted FDA clearance as a therapeutic product for smoking cessation. The FDA has approved NRT and prescription medications (varenicline, bupropion) as cessation aids, but not e-cigarettes.
• WHO: The WHO does not recommend e-cigarettes as cessation aids and calls for stronger regulation. It notes insufficient evidence to support their use for cessation at a policy level, and expresses concern about their global promotion.

A 2019 randomised controlled trial published in the New England Journal of Medicine (Hajek et al.) found that e-cigarettes combined with behavioural support produced higher quit rates than NRT alone at 1 year (18% vs. 10%). However, 80% of those who had quit using e-cigarettes were still vaping at 1 year, compared to 9% of the NRT group still using NRT.

Dual use - using both e-cigarettes and conventional cigarettes simultaneously - is common, and it is an important issue to understand. Many people switch to vaping intending to quit smoking, but end up using both products.

The health implications of dual use are significant:

• No meaningful health benefit: The health benefits of smoking reduction come primarily from the elimination of combustion products. Studies suggest that dual users - who still smoke some conventional cigarettes - do not achieve the cardiovascular and respiratory benefits that come from complete cessation.
• Maintained nicotine dependence: Dual use keeps the addiction active, making eventual complete cessation harder.
• False security: Some dual users feel they are making progress toward quitting when they have effectively just added a new nicotine delivery method.

If you choose to use e-cigarettes as part of your quit attempt, the advice from the NHS is clear: the goal should be to switch completely from cigarettes to e-cigarettes, and then to work toward stopping vaping as well. Continuing to smoke any conventional cigarettes alongside vaping provides minimal health benefit. If switching has not helped you stop smoking, speak to an NHS Stop Smoking Service or your GP about other options.