Table of contents
DOI: https://doi.org/10.58248/RR103
Background
Research shows that vapes are a more effective smoking-cessation tool than other nicotine replacement products. Research also shows that while vapes are less harmful than tobacco products, they can have negative effects on health.
In 2024, the number of people who vape in Great Britain exceeded the number of people who smoke for the first time. Vaping is increasing among 11-to-17-year-olds and among those who have never smoked. Of those who vape in Great Britain, 90% of 11-17-years-olds, and 80% of adults use vapes containing flavoured liquids (also known as ‘e-liquids’).
The extent to which vape components and e-liquids cause harm is not well understood. However, some countries, such as New Zealand and the Netherlands, have banned certain e-liquid flavours (excluding menthol and tobacco). Evidence suggests that actions by some regions to ban certain e-liquid flavours can reduce vaping. However, evidence also suggests that banning e-liquid flavours may have unintended consequences, including more people buying and using illicit and/or vaping unregulated products. The resulting harms or benefits are likely to depend on how restrictions are designed and enforced.
A key policy challenge is reducing vaping by children and by those who have never smoked, while ensuring access to adults for whom flavoured vapes are an effective tool for quitting smoking.
Regulation of vapes and vaping devices
The Tobacco and Vapes Act 2026 restricts the accessibility of vapes, including nicotine-free vapes, and gives the government powers to regulate ingredients and flavours. The Act seeks to reduce vaping in children, while ensuring continued access to vapes for adult smokers for whom flavoured vapes are an effective tool for quitting. It also gives the government powers to regulate vaping product standards, e-liquid ingredients and e-liquid flavours. An area of scientific uncertainty is the safety profile of inhaling e-liquid ingredients that are characterised as safe to use in foods.
The Tobacco and Related Products Regulations 2016 regulate the liquid tank capacity of vape devices (as well as the nicotine concentrations of e-liquids), but not other device functions, such as the power they generate to heat e-liquid.
What are the components of vape devices?
Vapes contain:
- a mouthpiece
- a liquid tank or cartridge
- a heating element (atomiser or coil) to heat e-liquid and generate the aerosol
- a microprocessor that controls temperature battery safety and LED displays
- an on/off switch
- a rechargeable lithium battery
In a vape, battery power heats the coil, to heat the e-liquid in the tank. This generates aerosols transmitted via the mouthpiece.
Figure 1: Different types of vapes and their components
Source: U.S. Fire Administration, Electronic Cigarette Fires and Explosions in the United States 2009 – 2016; Granada, S., Vivarelli, F. and others, Toxicological Aspects Associated with Consumption from Electronic Nicotine Delivery System (ENDS): Focus on Heavy Metals Exposure and Cancer Risk, 2024.
How can vape devices’ settings affect the vaping experience?
The aerosol temperature that a vape produces affects a person’s vaping experience. This is because higher temperatures change the feeling of the aerosol in a person’s throat, lead to higher concentrations of nicotine being delivered to the lungs and increase the intensity of an e-liquid’s flavour.
The temperature of the aerosol produced depends on power settings, coil design, the airflow, an e-liquid’s composition, the wick saturation and a user’s ‘puffing behaviour’.
Generally, if a vape has high power settings, its coil can reach higher temperatures. Vapes with:
- low power settings (7 W to 15 W) can reach temperatures of up to 190°C
- medium power settings (15 W to 40 W) can reach temperatures of between 190°C and 260°C
- high power settings (greater than 40 W) can reach temperatures of over 260°C
The resistance of a vape device’s coil (which determines how electricity flows) also influences aerosol temperatures. Low-resistance coils permit higher temperatures. The combination of power and coil resistance influences the properties of the aerosol produced by a vape:
- High-powered/low-resistance vapes produce more richly flavoured, warmer aerosols. They are promoted by manufacturers as “direct-to-lung” vapes.
- Low-powered/high-resistance vapes produce cooler aerosols and a smoother experience. They are promoted by manufacturers as “mouth-to-lung” vapes.
What are the health effects of different vape device settings?
Research shows that vape temperature can influence health risks.
Heating the coil to vaporise e-liquid generates toxic and carcinogenic compounds, including:
- aldehydes (including acetaldehyde, acrolein and formaldehyde)
- free radicals
- reactive oxygen species
- metals
Some of these compounds are also produced by cigarettes, and cause lung inflammation. Long-term exposure to these compounds is associated with a range of lung diseases including cancer.
In a typical low-powered vape, some of these compounds are produced at levels which become toxic and harm human cells and tissue. As the power and aerosol temperatures produced by vape devices increases, this alters aerosol toxicity.
There is limited evidence on how vape device settings affect long-term health. Data on how these compounds cause smoking-related diseases has led scientists to infer that, since higher-temperature vapes create more toxic aerosols, it is reasonable to assume that vapes with more powerful device settings are likely to be more harmful.
What ingredients do vape e-liquids contain?
Different brands make e-liquids in various formulations. A 2021 study of vapes sold in the UK found that e-liquids contained 17 ingredients on average, and identified over 1,500 different e-liquid ingredients in the products examined. E-liquid ingredients typically include:
- solvents to carry flavourings, such as vegetable glycerin and propylene glycol
- nicotine
- flavourings and other ingredients
Recent evidence suggests that another common e-liquid ingredient is ethanol, although its purpose and health effects are not well researched.
E-liquids may also contain impurities such as metals, phthalates and forever chemicals (perfluoroalkyl and polyfluoroalkyl substances, or PFAS, which take a very long time to degrade). These impurities originate from manufacturing processes, storage conditions and regular vape device use, when the e-liquid interacts with other materials in a device, such as metallic coils and plastic components.
Nicotine
Nicotine is highly addictive and has well-established short and long-term health effects. A typical cigarette contains 11 to 15 milligrams (mg) of nicotine, of which 1 mg to 2 mg is inhaled. Vape devices contain e-liquids with a range of nicotine concentrations and deliver a much higher proportion of nicotine than cigarettes. Generally, about 90% of the nicotine in an e-liquid is inhaled.
The amount of nicotine in vape e-liquids is regulated; the concentration must not exceed 20 mg per millilitre (or 2%). 18 to 20 mg per millilitre is considered a high concentration: 1 millilitre of 20 mg per milligram e-liquid is equivalent to 20 cigarettes. People who vape to help themselves quit smoking often choose vape nicotine strength based on their smoking habits, with moderate to heavy smokers tending to prefer higher levels of nicotine (above 10 mg).
Nicotine for vapes can be bought in different formulations, such as ‘freebase’ nicotine (the purest form of nicotine) and nicotine salts. Nicotine salts change the rate at which nicotine passes from the lungs into the bloodstream. This enables low-power vapes to give a so-called ‘smoother’ experience while providing a stronger, quicker and longer-lasting nicotine hit.
Vegetable glycerin/propylene glycol
Vegetable glycerin (VG) and propylene glycol (PG) are widely used in pharmaceutical and cosmetic products, and as food additives. Although substances are certified as safe to eat, this does not mean they are safe to inhale.
The ratio of VG to PG used in a vape influences the flavour, feel in the throat and aerosol formation. The mixture of VG and PG can be personalised by the user or store-bought, with common ratios including 50/50, 70/30 and 80/20.
What are the health effects of VG/PG?
VG and PG degrade when heated, generating toxic and carcinogenic compounds which increase the risk of developing cancer. These compounds are also found in cigarette smoke. Liquids with a high ratio of VG require higher temperatures (220°C to 250°C) to vaporise effectively. PG-based e-liquid solutions are associated with increased carcinogenic compound generation.
Flavourings and other ingredients
How many e-liquid flavours are available in the UK?
E-liquid flavourings are natural or artificial. In the EU and the UK, the most frequently added flavouring agents are ethyl butyrate, vanillin and ethyl maltol.
UK consumers can choose from over 4,000 e-liquid flavours, from sweet (candy, bubblegum, toffee) to sour (apple, watermelon). A choice of e-liquid flavours may make vapes more attractive to children and young people. Research also indicates that flavours are part of the appeal for those who want to stop smoking, with 50% of ex-smokers using fruit-flavoured vapes and 22% using menthol-flavoured vapes.
In 2025, Action on Smoking and Health conducted a survey on vape use among young people and a survey on vape use among adults in Great Britain. The surveys found that vapes with:
- fruit flavours were preferred by 59% of 11-to-17-years-old and 51% of adults
- other sweet flavours (chocolate, desserts, vanilla, candy, energy drink, soft drink) were preferred by 17% of 11-to-17-year-olds
- menthol/mint flavours were preferred by 20% of adults.
What are the health effects of flavourings?
Flavouring ingredients are linked to poorer lung health, as they cause lung inflammation. Heating flavoured e-liquids also produces high levels of aldehydes, increasing vape toxicity. Other common flavouring agents such as cinnamaldehyde decrease lung function by irritating the respiratory tract. Because e-liquids comprise several compounds, the product formulation may increase associated health risks. For example, vanillin reacts with PG, producing high levels of compounds that are toxic to the lungs.
Due to the variety of ingredients available, the lack of research and the different product formulations available, it is difficult to draw consensus conclusions on the health effects of flavoured e-liquids. However, cell, animal and toxicity studies show that aerosols generated from e-liquids can damage lung and immune cells, particularly if they are flavoured. Flavoured e-liquid aerosols are linked to increased respiratory sensitivity. In animal studies, e-liquid aerosols containing flavours and nicotine impaired lung function and health when compared with non-nicotine or unflavoured e-liquids. Mixing flavours when preparing e-liquids also increases aerosol toxicity.
Scope and quality of research
The wide range of device settings and e-liquid flavouring ingredients makes it difficult to assess the health effects of vaping. Composition varies across brands, and different ingredient combinations can lead to varied chemical interactions.
Evidence on how device settings and e-liquid composition affect health is limited. Larger population studies are a strong method to examine how factors such as device settings, PG/VG ratios and flavoured e-liquids contribute to harm, building on existing cell research and animal research. Research that follows people who vape over time would help to clarify both the short-term and long-term health effects of vaping.
Academic research on the effects of vaping is beginning to explore how device personalisation (such as modifying coils and temperature) influences toxicity, which may inform policy. However, this research is challenging due to the range of variation in vape devices, e-liquid ingredients and user behaviours.
While lungs are developed by around age 8, full lung maturation continues into a person’s mid-twenties. Studies examining how vaping affects lung development across childhood and adolescence would improve understanding of potential risks.
Policy considerations
Although some requirements indirectly limit vape power output, there are currently no restrictions regarding power (W) and coil resistance. The Tobacco and Vapes Act 2026 gives the Government the powers to regulate vapes’ “technological features”, including via provisions about software in vaping products.
Scientists suggest that emerging research on vape design features, including power settings and vaping temperatures, will inform future policy decisions that aim to minimise harms.
Ongoing monitoring of vaping in children and young people is widely considered to be important. Stakeholders comment that monitoring children’s vape use is important for identifying how the availability of flavours may influence their use, and to inform ongoing policymaking to minimise risks to children.
Acknowledgments
POST is grateful to Rute Santos, whose Parliamentary PhD fellowship was funded by BBSRC (UKRI), for researching and writing this briefing.
Questions about this briefing should be referred to Clare Lally, who acted as parliamentary lead for this work.
POST would also like to thank the following people for kindly giving up their time during the preparation of this article:
- Ana M. Rule, PhD, MHS, Associate Professor of Environmental Health and Engineering, Johns Hopkins University
- Dr Aaron Scott, Associate Professor in Respiratory Science, University of Birmingham