How much horrible gack is it possible for my lungs to actually contain? ???

[Q0FE]

Been ill for days with a nasty chesty cold bug, feeling really wiped out, high temperature, all that. Ive been coughing and coughing for days until me chest and back hurt, but yesterdat i started constantly coughing up nasty tasting phlegmy stuff (as in a mouthful of it every 5 mins or so) and today looks to be going the same. My chest is all rattly when I breathe so I guess there's more to come

But how can there BE so much gack in my lungs without me drowning or something??