[Bill S (OP)]

I’ve just been talking to someone who says that a good way to kill yourself would be to have a cylinder of hydrogen and inhale it; because, he says, the brain doesn’t distinguish between hydrogen and oxygen, so doesn’t cause a “panic” reaction.

He is seriously considering suicide. Does he have this right?

[chiralSPO]

Yes, that is true, but it's not just hydrogen--nitrogen, helium, argon, and any other non-oxygen gas other than CO₂. Our brains are not capable of measuring how much oxygen is around, and instead depend on measuring the concentration of CO₂, so as long as there is no CO₂, the "panic" reaction will not be activated. (fun fact: breathing a mix of gasses that has the same concentration of O₂ as air, but highly elevated CO₂ concentration will cause the panic response.)

I would urge your friend to reconsider.

https://suicidepreventionlifeline.org/

[Bill S (OP)]

Thanks Chiral. In several years of working with people who attempted suicide, this is one method of which I had no personal experience.  Plenty of CO, Paracetamol etc; even one young woman who took an overdose of contraceptive pills. 

I would urge your friend to reconsider.

Still working, gently, on that.

[Bored chemist]

Am I the only one who is worried that by saying " He's more or less right- teh brain won't notice the lack of oxygen and kick in the  panic reflex", we are effectively saying
"gases that are free from oxygen are a good way to top yourself"?

I really don't think we should be providing that advice.

[evan_au]

I am worried that anyone who would fill a space with hydrogen gas is going to have some volume of a highly explosive mixture that could kill numerous people, given even a tiny spark.

Large volumes of Hydrogen must be handled with great care (the tiny amount used in the traditional "pop" test is not too dangerous, provided the test tube is open-ended).

[chiralSPO]

Am I the only one who is worried that by saying " He's more or less right- teh brain won't notice the lack of oxygen and kick in the  panic reflex", we are effectively saying
"gases that are free from oxygen are a good way to top yourself"?

I really don't think we should be providing that advice.

I understand your concern here.

On the other hand, I'm not sure I have provided any real information that isn't available elsewhere (or by common sense). Other deadly inhalants include liquid water, chocolate syrup, and lava (this last one does elicit the panic response, but death is so very fast, I doubt it would matter).

Again, suicide is NOT recommended! https://suicidepreventionlifeline.org/