Table of Contents
- DOES DIACETYL IN VAPING CAUSE POPCORN LUNG?
- INTRODUCTION
- WHAT IS POPCORN LUNG?
- WHY IS IT CALLED POPCORN LUNG?
- WHAT CAUSES POPCORN LUNG?
- HOW IS POPCORN LUNG DIAGNOSED AND TREATED?
- WHAT IS DIACETYL?
- WHAT IS DIACETYL USED FOR?
- IS DIACETYL USED IN VAPING?
- WHAT DOES THE EVIDENCE SAY?
- SHOULD YOU WORRY ABOUT DIACETYL IN YOUR VAPE?
- DOES DIACETYL IN VAPING CAUSE POPCORN LUNG - CONCLUSION
- REFERENCES
KEY TAKEAWAYS
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Diacetyl Is Linked to Popcorn Lung - but It’s Banned in UK E-Liquids
Diacetyl, a buttery flavouring once linked to “popcorn lung,” is prohibited in UK-regulated vape products under TPD laws. -
UK Vape Products Are Diacetyl-Free and Strictly Regulated
Reputable UK brands, like SMOKO, do not use diacetyl and must meet stringent safety standards, making them a safer choice. -
Popcorn Lung from Vaping Is Extremely Rare/Non-existent
There’s no proven link between modern, legal vaping and popcorn lung in the UK - especially when using tested, compliant e-liquids.
DOES DIACETYL IN VAPING CAUSE POPCORN LUNG?
Cancer Research UK indicates there have been no confirmed cases of popcorn lung vaping reported in people who use E-Cigarettes. Diacetyl causes popcorn lung when inhaled in sufficient amounts – like the popcorn factory where workers were inhaling a lot – and while it has been found in E-Cigarettes overseas, the amounts are likely too small to cause harm. However, diacetyl is banned from e-liquids in the UK and the EU for safety.
INTRODUCTION
*2024 Update - You can enjoy SMOKO's UK-made liquids in the New SMOKO VAPE POD! A pre-filled pod style vape that is sleek and discreet!
With electronic cigarettes being declared “at least 95% less harmful than cigarettes” according to Public Health England and backed up by Cancer Research UK and the NHS it might seem that the question of whether E-Cigarettes are bad for you has been settled.
However in 2014 a US study came out that showed that some e-liquids had Diacetyl included, a chemical which when vaporised can cause illness and even death by “popcorn lung”. This caused news headlines to declare E-Cigarettes as dangerous, and they haven’t really stopped since then.
They both can’t be right, so who is correct? Strangely enough the answer to that depends on where you are buying your E-Cigarettes from. If you are in the UK or EU then this isn’t an issue as none of the flavoured e cigarettes will have Diacetyl in, if you are in the US however popcorn lung might be more of an issue.
WHAT IS POPCORN LUNG?
Before we go on though we should know what popcorn lung is. Popcorn lung is a rare disease in which the lungs’ airways become stiff and scarred.
It’s proper name is bronchiolitis obliterans though sometimes the name is abbreviated as BO, and occasionally called constrictive bronchiolitis. Popcorn lung is scarring of the smallest airways within the lungs (bronchioles) and damage these tiny air sacs. By doing this the lungs capacity to hold air and the efficiency in which they transfer that to the blood are dramatically reduced.
WHY IS IT CALLED POPCORN LUNG?
Bronchiolitis obliterans got its nickname from where it was first found, a popcorn factory.
In 2002 the CDC (the Centers for Disease Control and Prevention) found 8 cases of bronchiolitis obliterans (popcorn lung) in the employees in a Missouri microwave popcorn factory. As this illness is rare they investigated further and found that those with the worst lung damage had spent the most time mixing in the flavourings, and so had the most exposure to diacetyl with hot oil in large industrial vats.
As diacetyl is considered “safe” by the FDA to eat and drink, the owners of the factory had thought nothing of using the chemical with the boiling oil to give their popcorn a more buttery taste.
WHAT CAUSES POPCORN LUNG?
Bronchiolitis obliterans (popcorn lung) can result from of a variety of causes such as inhaling chlorine, ammonia, sulfur dioxide, and metal fumes from welding. However, diketones (a type of chemical) like diacetyl are the chemicals most often associated with popcorn lung.
Diacetyl is actually considered safe when eaten and drank, but when breathed in it damages the lung cells. After diacetyl has made its way into these cells they become inflamed and damaged and more susceptible to viral, bacterial and fungal infections.
HOW IS POPCORN LUNG DIAGNOSED AND TREATED?
One of the scary things about popcorn lung is that it is extremely hard to detect early and there is no way to cure someone with it without a lung transplant. This is because bronchiolitis obliterans causes scarring of the lung tissue and blocks the airways, which prevents the lungs from functioning properly.
The symptoms of popcorn lung are very similar to those of another lung disease called COPD (chronic obstructive pulmonary disease), which is caused by cigarette smoking, but for popcorn lung the symptoms can appear within just 2-8 weeks.
What makes it difficult to detect is that a lot of the early symptoms resemble a common cold or flu. Early bronchiolitis obliterans symptoms include:
Getting short of breath
Difficulty exercising
Fatigue
Nose, mouth, and eye irritation
Other respiratory diseases
Wheezing
Getting short of breath
Difficulty exercising
Fatigue
Nose, mouth, and eye irritation
Other respiratory diseases
Wheezing
Without treatment the disease gets progressively worse and in the long term can even lead to death if left unattended. If caught early the illness is manageable with a treatment typically consisting of steroids and antibiotics. However if the illness is caught late, the best option will be a lung transplant.
WHAT IS DIACETYL??
You may be wondering at this point what exactly this chemical actually is. On it’s own it is a clear yellow liquid with a strong smell of butter. It is an organic chemical that can be found in fermented products like alcoholic drinks and in dairy products like cheese or butter.
Diacetyl is actually part of the reason that cheese and butter have that distinct buttery flavour, and why the microwave popcorn factory used diacetyl for their popcorn.
It’s also found naturally in some fruits and tobacco (most dangerous chemicals do end in tobacco for one reason or another).
As a chemical it is fairly harmless unless it is turned into vapour, when it can harm your lungs and cause permanent damage.
WHAT IS DIACETYL USED FOR?
After reading all this it may seem insane to use a chemical like this. But as we have said before, if you eat or drink diacetyl it is fine for you.
The FDA (the US Food and Drug Administration) classes diacetyl as “generally recognised as safe” (1), which might not seem to be a glowing recommendation but is what most ingredients which are safe to eat are classified as.
Because of its buttery taste and smell, plus its ability to enhance sweet flavours, diacetyl is mainly used as for artificial food flavourings. It adds that buttery flavour and smell to sweets, popcorn, baked goods, beer, wine and more.
And for years there has been no trouble with it, any diacetyl that was vapourised when consumers used it would have been in such small quantities that it would have been negligible.
However that changed when people started adding it to flavoured e-cigarettes.
IS DIACETYL USED IN VAPING?
As we come to the part of the article where we are talking about Diacetyl and E-Cigarettes it’s important to state this right now: any legal E-liquid made or sold in the UK or the EU will not have any Diacetyl or other potentially harmful chemicals in.
Though SMOKO had this policy since we began in 2012 it became the law in 2016 according to the the Tobacco Products Directive (TPD). Amongst many other health and safety rules to make sure that E-cigarettes were as safe as they can be, one of them was that they couldn’t include Diacetyl, Acetoin, Pentanedione or a large number of other chemicals that might harm you.
For the last 6 years all E-liquids and E-Cigarettes made in the UK (like all our liquids are) have been clear of this issue and safe to use. That’s why Public Health England is confident that E-Cigarettes are 95% less harmful than cigarettes (2), and why the NHS actively encourages smokers to use e-cigarettes to help get off the tobacco (3).
The same kind of tight regulation on E-Cigarettes though cannot be said for all other countries, including the USA.
Over the pond diacetyl is still being used as one of the flavouring chemicals in sweet flavoured e-cigarettes, especially candy flavours.
This might seem crazy, but diacetyl is a widely used ingredient in many food and drink products, and is still considered safe by many manufacturers. Though not all e-liquids and e-cigarettes in the USA have diacetyl, there are still a number of brands that do.
That isn’t for lack of trying by health agencies and charities. One of the larger charities, the American Lung Association, have been pushing for a change in E-Cigarettes (4).
The good news is that this might be changing, but not until 2022. After that the US will hopefully have similar rules to the UK. That includes submitting products for review and making sure that chemicals that might be harmful aren't added.
A question you might be asking yourself now is why, then, doesn’t the US seem to care as much about Diacetyl than the UK and the EU? The answer is complex, but one of them is that is that there simply isn’t much concrete evidence against Diacetyl in e-cigarettes (5), and even that evidence is from small studies.
WHAT DOES THE EVIDENCE SAY?
After all you have read it might seem the most obvious thing in the world to get rid of Diacetyl, but from a scientific standpoint the studies are extremely small. They all point to Diacetyl being dangerous when vapourised in large quantities, but to ban a widely used chemical it takes a lot of data and takes a long time, which sadly none of these studies are able to provide.
There have only been 3 studies on Diacetyl, and only 2 of them are to do with Diacetyl in E-Cigarettes.
The 1st study we have already talked about, and that is the one conducted by the CDC which discovered that popcorn lung existed in the first place (6). This was back in 1992, well before E-Cigarettes were invented, so there was obviously no mention of them in the study.
However it does show that in very large quantities over a long period of time Diacetyl does cause popcorn lung. We know that it takes a while, and that it takes a lot of the vapourised Diacetyl as it was only the people who stood directly next to it for over 12 months had the major symptoms, people further away either had none or much milder symptoms.
The other 2 studies though do focus on Diacetyl in E-Cigarettes. The study that most people quote is a 2014 paper by cardiologist Konstantinos Farsalinos and his team. In it they compared 159 different e-liquid from 36 manufacturers and retailers in 7 countries (7).
The liquids were tested and found that 74% of all the liquids had some level of Diacetyl, with 47% of those Diacetyl containing liquids producing more than the safe limit.
The study didn’t say how damaging these levels of Diacetyl could be, or whether there was enough Diacetyl in the vapour to cause popcorn lung.
The 3rd study from 2019 tries to address this. In the new study, researchers used new lab techniques that allowed them to examine the impact of both diacetyl and 2,3-pentanedione on cells (8) in a system that closely mimicked the human airway. They exposed normal human bronchial epithelial cells to the chemicals for 24 hours. They found that both diacetyl and 2,3-pentanedione were linked with changes in gene expression that could impair both the production and function of cilia.
SHOULD YOU WORRY ABOUT DIACETYL IN YOUR VAPE?
The evidence isn’t quite damning, both studies on Diacetyl in e-cigarettes have been small, but all three studies are showing a pattern of what Diacetyl could do if inhaled for long enough. And after all, Diacetyl isn’t needed in E-cigarettes so why take the risk when you don’t have to?
That was the thinking of the TPD and so if you are worrying about popcorn lung, just make sure to buy from a UK company like SMOKO and you will be good to go. In the UK we have been selling e-cigarette starter kits like this which are free of all known harmful chemicals since 2012, and have been submitted to the MHRA (Medicine and Healthcare Regulatory Agency).
However if you want to be really sure, you can avoid any flavours that would have a buttery flavour like custard and focus on the fruit flavours and you will be fine.
If you are in the US you can always buy from a UK brand or look for brands that advertise their lack of Diacetyl. If you are planning to do this though make sure that you don’t get a liquid with a substitute for Diacetyl, as some of them can also be dangerous.
Substitutes for Diacetyl to look out for are:
- Acetoin: According to the U.S. National Library of Medicine, this chemical can contribute to respiratory issues after prolonged inhalation.
- Acetyl propionyl: A 2012 study in the journal Toxicologic Pathology showed that inhaling this chemical in high doses caused lung damage, respiratory tract inflammation, and death in rats.
*2022 Update - The PACT act has put E-Cigarettes on the prohibited list for most US shipping services. Until this changes, we are unable to send to the United States.
DOES DIACETYL IN VAPING CAUSE POPCORN LUNG - CONCLUSION
To sum this all up, if you are buying from a UK company like SMOKO, popcorn lung is not something you have to worry about at all. The only way you could be conceivably exposed to it would be if you went out of your way to buy homemade or illegally imported liquid from the US which might have Diacetyl in.
If you buy from a legal company in the UK you can be safe in the knowledge that all the products have been tested and approved for use.
And if you are a smoker who is looking to quit you can be sure that, like Public Health England and the NHS keep insisting, that by making the switch to an E-Cigarette you are moving to a product that is at least 95% less harmful than cigarettes.
Ready to quit smoking? Check out the SMOKO Starter kit range that uses great-tasting UK made liquids, free from diacetyl!
*2023 Update - Now you can pick up a starter kit for one of our cigalikes for FREE* when you buy a box of E-Cigarette refills! *(One per customer)
FAQ: DOES DIACETYL IN VAPING CAUSE POPCORN LUNG?
Q1: What is diacetyl?
A: Diacetyl is a chemical used to create buttery or creamy flavours, once found in microwave popcorn and some e-liquids. It has been linked to a rare lung condition known as bronchiolitis obliterans, commonly referred to as “popcorn lung.”
Q2: What is popcorn lung?
A: Popcorn lung is a serious but rare lung disease that causes scarring and narrowing of the airways, leading to symptoms like coughing, wheezing, and shortness of breath. It was first associated with workers in popcorn factories exposed to high levels of diacetyl.
Q3: Is diacetyl still used in vape juice?
A: No. In the UK and EU, diacetyl is banned from all e-liquids under the Tobacco Products Directive (TPD). Reputable brands like SMOKO ensure their products are diacetyl-free and fully compliant with UK safety standards.
Q4: Can vaping cause popcorn lung?
A: There is no confirmed case of popcorn lung caused by vaping. Especially in the UK, where e-liquids are strictly regulated and tested, the risk is extremely low when using legal and tested products.
Q5: How can I stay safe when vaping?
A:
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Buy e-liquids from trusted UK brands
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Check for TPD compliance and lab testing
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Avoid unregulated or imported products not approved in the UK
REFERENCES
(1) U.S Food & Drug Administration: Code of Federal Regulations Title 21
(2) E-Cigarettes around 95% less harmful than tobacco estimates landmark review
(3) Using e-cigarettes to stop smoking
(4) Popcorn Lung: A Dangerous Risk of Flavored E-Cigarettes
(5) Does vaping cause popcorn lung?
(6) Occupational Exposure to Diacetyl and 2,3-Pentanedione
(8) Common e-cigarette chemical flavourings may impair lung function
ABOUT THE AUTHOR
Written by Mike Cameron
Mike Cameron is a former smoker of 15 years (2 packs a day) until he successfully quit using a cigalike. Mike is the Co-Founder and CEO of SMOKO E-Cigarettes and over the last 10 years, SMOKO has prevented 600M+ cigarettes from being smoked, helped their customers save £320M+ of their hard-earned money from going up in smoke and helped 10,000’s of adult smokers in 25+ countries to live smoke-free.
Last updated 31/07/2025
