What do you think about using Carbon Monoxide instead of Helium in Final Exit method?

There is room for error in all of them. There is an excellent chance of severe brain injury, but not death, with them. This leaves the person unable to care for themself but living for many years to come. And there are the idiots who mess up suicide by gas and end up living while killing others in their buildings when the gas leaks into other homes/apartments. They get both brain injury and criminal/civil litigation. If they thought life was bad before, this often just makes it worse.