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Inhaling helium and talking with a funny voice used to be a great party trick for chemists with access to it and has now become more popular as helium supplies have become accessible for filling balloons.

But claims are being brought forth that helium inhalation is dangerous. This BBC story claims a teenager died from it.

Members of the public will be more familiar with the usually harmless and not uncommon party trick, of inhaling helium from a balloon to a high-pitched squeaky voice.

It must be recognised that such activity can, on rare occasions, lead to adverse health effects and some deaths have been reported.

Breathing in helium displaces oxygen from the lungs which in turn, deprives vital organs of essential oxygen.

But if helium is the most inert element, how can it be deadly, and if so, why?

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    That it is inert has nothing to do with the potential dangers. Helium is not oxygen, so you can of course suffocate if you replace all the air in your lungs with helium. The interesting part of an answer would be some detail about the conditions under which helium is dangerous, as it is lighter than air it usually leaves the lungs easily as far as I know. – Mad Scientist Jan 26 '14 at 23:24
  • @Fabian Thats why I asked it. I hope that some useful data will emerge (I already have some but will give others a change to write it up before I do). I agree with your assessment of what would be interesting in a good answer. – matt_black Jan 26 '14 at 23:27
  • Removed off topic comments – Sklivvz Jan 29 '14 at 9:53
  • According to our Privileges section, you should only use comments to request clarification from the author or leave constructive criticism that guides the author in improving this post. Please review the When shouldn't I comment? section and act appropriately in the future. Use the Skeptics Chat for general discussion. – Sklivvz Jan 29 '14 at 19:23
  • The last paragraph of your quote answers your question. – OrangeDog Aug 29 '14 at 16:23
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Helium inhalation rarely causes negative effects in the long term, as the gas is inert and can't bond to haemoglobin within the blood (diffusional hypoxia - a common cause of illness after inhaling other gases).

Because, generally speaking, a person inhaling helium does so from a balloon, the loss of consciousness will usually result in the restore of the oxygen supply, it's not usual to suffer ill affects from Helium. If a person were in an atmosphere of helium, or if they were somehow attached to Helium delivered by a mask, this can lead to complete asphyxiation, and death from Hypoxia (lack of oxygen to tissues within the body).

Importantly though, inhaling Helium can on rare occasions cause the formation of a Gas Embolus (a blockage in a vein caused by the presence of a bubble of gas), which can easily kill, or cause significant damage. The risk is increased if the Helium is increased from a pressurised source, rather than inspired by the person because a pressurised source can caused injury (barotrauma) to the pleura of the lungs, leading to Helium building up in the lungs. Technically this could actually cause a pneumothorax (collapsed lung) but this would be rare.

Medscape article on Helium Inhalation

This is notably different to inhalation of some other gases which people also deliberately inhale, such as Nitrous Oxide, which is popular in some European holiday destinations. Nitrous Oxide will cross the alevolar wall by diffusion, and will bond to Haemoglobin in the blood, which displaces the ability of this haemoglobin to bind to oxygen instead. This affect is called Diffusional Hypoxia, and can kill because, even after inhalation stops, the ability of haemoglobin to carry oxygen takes time to restore.

Diffusion Hypoxia

The short version is, it rarely causes any harm, but a on unlucky occasions it will, and this could be fatal.

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    Oh and the BBC are wrong that breathing in Helium 'displaces oxygen' - that requires a reactive gas. – Owen C. Jones Jan 29 '14 at 14:09
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    Why doesn't helium displace oxygen? If I have a jar full of oxygen (or even plain air) and squirt helium into it before capping it, hasn't the helium displaced the oxygen in the jar? Likewise, if I have lungs full of air and inhale only helium from a big balloon, won't the helium displace the usable oxygen from my lungs? – Johnny Jan 31 '14 at 23:01
  • Because displace in this sense means within the bloodstream. When air is breathed in, oxygen bind to Haemoglobin in the bloodstream - the haemoglobin becomes Oxyhaemoglobin. When something like Carbon Monoxide binds to Haemoglobin, it prevents Oxygen from doing so - reducing the ability of blood to carry oxygen. This is what is meant by displacing oxygen, and because Helium can't bind to Haemoglobin, it can't displace oxygen in that sense. In the sense of volume, it can, but it would only take up space until the person breathed out again, which is less than 2 seconds, typically. – Owen C. Jones Feb 3 '14 at 18:00
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    IN what sense? The BBC article didn't say anything about the helium binding with hemoglobin - it said that Helium displaces oxygen in the lungs (it does). – Johnny Feb 3 '14 at 20:34
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Yes helium can be dangerous, but usually because of other risky behaviour associated with taking it

Statistically speaking it looks as though helium is associated a small, but increasing number of deaths. The following picture is based on mentions of helium on English death certificates (original source this tweet):

english helium deaths

But this doesn't help understand whether the problem is that the gas was helium or whether the users were doing something else that created or exacerbated the risk. Since helium is inert and doesn't have any direct physiological affects (though there are some small positive effects, see next reference) it is a little implausible that it is the direct primary cause of death. Helium is used safely in medicine and deep sea diving in gas mixtures that also contain oxygen.

Of course, pure helium will displace oxygen leading to potential asphyxiation. But it isn't obviously easy to achieve that just by breathing it from a balloon. If you inhale enough to become unconscious, you won't breathe any more of the helium and the worst risk is likely to be related to fainting. As soon as you fall you are in air and will regain the required supply of oxygen on refilling your lungs. As this Slate article explains:

You don't have to worry about fatal asphyxiation if you're sucking from a helium balloon at a party. At worst you'll keep going until you get lightheaded and pass out—at which point you'll stop inhaling helium and your body's oxygen levels will return to normal. Of more concern is the possibility that you'll hurt yourself when you fall down.

Industrial accidents involving asphyxiation usually involve closed spaces filled with inert gas. If you faint in one of these, you are still in the dangerous, airless environment and will die quickly if not removed (see this example). It isn't easy to achieve this with helium as it is less dense than almost every other gas so will only fill spaces enclosed that are sealed completely or at the top. It has been done, though. Two students won a Darwin Award for dying after climbing into an 8' helium filled balloon in florida (reported here). In this case, though, monumental stupidity deserves a larger share of blame than helium.

There is another direct risk from trying to inhale helium, but again it isn't the helium that is the problem but the inherent risk of any compressed gas supply. As this bulletin from the Compressed Gas Association explains:

Attempting to inhale helium from a commercial helium balloon filling system poses a greater hazard than does inhaling helium from a balloon. Beyond the risk of passing out, the potential for fatal injury is present. Unfortunately, several young people have been killed while inhaling helium from such a system.

How can a healthy young person be killed by a seemingly harmless substance, you ask? Postmortem examinations of victims explain what occurs, while engineering analysis explains how.

Chemical reaction does not cause fatal injuries. Rather, the pressure of gas inside the lungs is the agent that can kill instantly. Autopsies show that the alveoli (air sacs) in the lungs have been ruptured. Death follows immediately, as the victims literally drown in their own blood. Under such circumstances, cardiopulmonary resuscitation is of no avail.

So, strictly speaking, the risk is gas pressure not helium.


To summarise

There is no physiological effect of helium that makes it risky to inhale.

But, if the user can contrive a situation where the helium completely displaces air, asphyxiation is possible. So don't climb into gas filled balloons or put bags over your head (these are bad ideas whatever the gas.)

Don't breathe any gas direct from the compressed supply, that is very risky because of the effect of uncontrolled pressure on your delicate lungs.

If you must inhale, do it from a small balloon in a room where you won't hurt yourself if you fall and where other, sober, people are present. The risks here are very low.

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    Don't underestimate the stupidity of kids trying to get a buzz -- Big balloons large enough to fit a head in are readily available, and I'm sure more than one inebriated college student has thought about filling such a balloon with helium or nitrous oxide. – Johnny Jan 31 '14 at 23:05
  • The first graph may show an increase in deaths mentioning helium from 2008 to now because it has become more common as a means of suicide. en.wikipedia.org/wiki/Suicide_bag#History – Ravenstine Mar 3 '15 at 4:29
  • I would like to add that another news source reporting the same story specifies that the girl put her head into the balloon: belfasttelegraph.co.uk/news/northern-ireland/… This definitely constitutes risky behavior -- suffocation could occur in this situation regardless of what gas the balloon was filled with. – MysteriousWhisper Mar 4 '15 at 21:47
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Not to dispute any of the other answers, but it may be worth noting that saturation divers breathe a mixture of helium and oxygen regularly, as helium does not have the same effects as nitrogen (neither the "nitrogen narcosis" cognitive effect and it desaturates from the blood stream faster).

What is saturation diving?

When in saturation the divers breathe a mixture of helium and oxygen (hence Mixed Gas), which saturates their body for the duration that they are at pressure (hence saturation).

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As reported in Frontline (http://www.pbs.org/wgbh/pages/frontline/suicide-plan/) inhaling helium is a popular way for assisted suicide organizations to help people die. A crude plastic hood is placed over the subject's head to induce suffocation while a tube connected to a helium tank pumps in helium. This gas is chosen because according to the organization it promotes a peaceful death experience. The use of helium in this manner may help explain the rise in helium-related deaths in the graph shown above.

This is not to say that the gas is dangerous in and of itself in lower inhaled amounts.

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    It's not that there's anything about helium that causes a peaceful death, but that it's the only gas readily available on the consumer market that won't cause symptoms or be dangerous. (Try to use a propane tank for suicide and you could end up with an impressive boom.) – Loren Pechtel Jan 31 '14 at 3:29

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