What Is In The Vapour Produced By E-Cigarettes?

24th Sep 2020

Originally Published: September 2020.

Last updated: July 2026.

Vaping products are for adult smokers and existing vapers only. Vaping is not risk-free. Not suitable for non-smokers or anyone under 18.

Quick Answer

The cloud a vaper exhales is water vapour, propylene glycol (PG), vegetable glycerin (VG), nicotine and flavourings, heated and turned into an inhalable aerosol rather than burned.

It looks like smoke, but it behaves very differently once it leaves your mouth: it dissipates in seconds rather than lingering in a room for half an hour, and it doesn't carry the thousands of combustion by-products that cigarette smoke does. Here's what's actually in it, and what that means for the people around you.

Vapour or Aerosol? The Terminology Vapers Get Wrong

Every vaper calls it “vapour”, and we will too for the rest of this article, but it's worth knowing that what you're exhaling is technically an aerosol - a suspension of tiny liquid droplets in air, not water vapour in the scientific sense.

The distinction matters because it explains why e-cigarette clouds behave so differently to cigarette smoke. Cigarette smoke is the product of combustion: burning tobacco releases solid particulates, tar and thousands of chemical compounds that hang in the air and cling to fabric.

Vaping doesn't involve combustion at all. The coil heats e-liquid to the point it becomes an aerosol, you inhale it, and what comes back out is mostly evaporating liquid droplets.

That difference shows up clearly in peer-reviewed research. A widely cited 2018 study published in the journal Nicotine & Tobacco Research measured particle concentrations in a room after vaping and after smoking. Particle levels from vaping returned to background within seconds.

After smoking a cigarette, particle levels stayed elevated for 30 to 45 minutes. That's the practical reason vape clouds vanish almost as soon as they appear, while a smoky room stays smoky.

What's Actually Inside the Cloud You Exhale?

Lifestyle image illustrating a realistic vape aerosol exhale during normal use. Strip away the branding and the flavour names, and almost every e-liquid on the market is built from four ingredients: propylene glycol, vegetable glycerin, nicotine (unless you've chosen a nicotine-free option) and flavourings. When you exhale, water from your own breath joins the mix too.

Propylene glycol (PG) is the workhorse carrier in most e-liquids. It's flavourless on its own, which is exactly why it's so good at carrying both flavourings and nicotine cleanly to the back of the throat, and it's the ingredient largely responsible for the “throat hit” that smokers switching over tend to recognise and, often, miss.

PG isn't exotic. It turns up in toothpaste, medicines, deodorants and hand sanitisers. A small number of people have a genuine PG allergy, and a somewhat larger number find high-PG liquids gave them a dry throat or a sensitivity reaction. If that's you, high-VG or 100% VG formulas are the usual fix, and our VSAVI 100% VG E-Liquids range is built specifically around that.

Vegetable glycerin (VG), by contrast, is the ingredient behind the thick, dense clouds cloud-chasers are after. It has a mild natural sweetness of its own, which is part of why high-VG liquids skew toward dessert and fruit flavours rather than the crisper tobacco profiles PG carries so well.

VG is also one of the least reactive substances used in consumer products, turning up in food, cosmetics and soap, which is exactly why it's the fallback for anyone who reacts badly to PG.

If you're weighing up which base suits you, our flavour and strength guide breaks down which formats pair best with which flavour styles.

Does Vaping Release Formaldehyde?

Close-up of vape e-liquid being dispensed into a bottle to illustrate the ingredients used in vape aerosol. This is one of the most persistent vaping myths, and it's rooted in a real but misapplied finding.

Formaldehyde, a known carcinogen also present in cigarette smoke, can form when e-liquid is overheated well beyond the settings any vaper would actually use, because it tastes burnt and unpleasant at that point.

Public Health England's 2018 evidence review, now maintained by the Office for Health Improvement and Disparities, found that at normal vaping settings there was no or negligible formaldehyde release, and concluded there was no indication that vapers using their devices as intended were exposed to dangerous aldehyde levels.

The practical takeaway is straightforward: stick to a lower-powered device set up correctly, avoid “dry hits” from an under-wicked coil, and this isn't something you need to lose sleep over.

Is Secondhand Vapour Something Your Household Needs to Worry About?

Adult using a vape device while seated outdoors, exhaling a light vapour cloud. This is one of the questions our customer service team hears most often from people considering switching, usually from someone who lives with a partner, parent or child and wants to do right by them before they buy a kit.

The short answer, per the NHS, is that e-cigarettes release very small amounts of nicotine into the surrounding air, and the available evidence suggests any risk to bystanders is small relative to tobacco cigarettes.

Unlike a lit cigarette, an e-cigarette produces no side-stream emission between puffs. All that reaches the room is the aerosol you exhale, and as covered above, that dissipates within seconds rather than settling into curtains, clothing or carpets the way cigarette smoke does.

The Royal College of Physicians' most recent evidence review reaches the same broad conclusion: vaping carries a small fraction of the risk of smoking, though it isn't entirely risk-free.

That last caveat matters, and we'd rather be straight with you than oversell it.

A 2024 study from University College London found that children living in homes where vaping happened indoors had measurably higher nicotine absorption than children with no exposure at all, though far lower than children exposed to secondhand cigarette smoke.

The researchers were clear that the difference in harm comes down to combustion: cigarettes burn tobacco and release thousands of toxicants alongside that nicotine, while vaping doesn't.

The sensible precaution, and the one the NHS recommends, is to avoid vaping directly around babies and young children where you reasonably can, in the same way you'd be mindful of any airborne exposure around a child. It isn't the same risk category as smoking indoors, but it's not nothing either.

If you're switching partly to protect the people you live with, a simple cigalike like the Vsavi Classic Starter Kit is usually the easiest first step: no e-liquid decisions to make, low vapour output, and pre-filled cartridges that pair naturally with familiar tobacco or menthol flavours if you're coming straight off cigarettes.

Key Takeaways

Vape vapour is an aerosol created by heating e-liquid, not burning tobacco.
Most e-liquids contain just four main ingredients.
The cloud disperses much faster than cigarette smoke.
UK evidence suggests vaping is significantly less harmful than smoking for adult smokers.
Avoid vaping around babies and young children where possible.

Frequently Asked Questions

Does e-cigarette vapour smell as strong as cigarette smoke?

It can smell noticeably strong depending on the flavour, but the smell clears far faster. Because the aerosol evaporates within seconds rather than lingering, flavour scent doesn't tend to soak into soft furnishings or clothing the way cigarette smoke does.

Can e-cigarette vapour set off a smoke alarm?

Standard photoelectric smoke alarms can occasionally be triggered by a large, dense cloud at close range, though it's uncommon with normal use. Heat-based alarms are far less likely to react.

Is vapour from a sub-ohm device more of a concern than a cigalike?

Sub-ohm devices produce noticeably larger clouds, so there's simply more aerosol in the air at any given moment, even though the underlying ingredients are the same. If household exposure is a concern, a lower-output device like a cigalike or MTL pod kit produces far less vapour to begin with.

Do all e-liquids contain nicotine?

No. Nicotine-free e-liquids are widely available and contain the same PG, VG and flavourings without the nicotine. Our range of flavours and strengths includes nicotine-free options alongside standard strengths.

About the Author

Joe Delaney looks after the day to day running of V2 Cigs UK and writes its blogs.

When the blog recommends a device, he has used it - and for a leak test that means actually filling kits and trying to make them fail, pocket-carrying them and leaving them upside down overnight, rather than repeating manufacturer claims.

Health, safety and regulatory points are checked against named UK authorities such as the NHS and MHRA, and a product is only ever called "less harmful than smoking" where a UK authority says so. More about how he works, and the family story behind V2, is on Joe's author profile.