Exactly. Your lungs don’t burn when you hold your breath because O2 is low, they burn because CO2 is high. Any other gas to displace the O2 is undetectable (aside from irritants and smells). It’s why huffing helium doesn’t burn but can make you light headed faster than you realize. That’s why CO poisoning is so dangerous. CO2 poisoning is torture. And yet CO2 pits are still legal for kill pits…