Breathing at that altitude must be like sucking meatloaf through a straw

Inhaling and exhaling aren't problems -- perfectly normal. It is just that the
inhaling part doesn't accomplish anything notably p[roductive. One probably
has 3-6 seconds of useful consciousness at 30K, no mask. Been there (in a tank
bolted to the floor) done that. Utterly unnoticed, utterly painless, kinda
fun, and REAL fast.

Quent