>>405834Most of those are heavier than air and displace oxygen, even if you filter them you're not breathing oxygen, and you're still going to die.
Gas mask is just stupid, it'll just make you sweat, it'll make you claustrophobic and reduce your vision.
And it will give you a false sense of security.
Proper way to do it is with a gas detector and a dust mask, but I just go in free with no mask and no detector, been doing it for years here in Nevada.
