Roybart, think about how nasty bongs and pipes get. That same oily smoke is coating the lungs. Terps are natural solvents and can loosen the stuff. Hot fresh solvents...
I notice that if I exhale some of the stuff I vape, out through my sinuses, I will sneeze.
Maybe the flowers do have dirt, because when I make butter from the ABV, the water is pretty darn nasty brownish.
As for dirt...Taking care of land, breathing pollen and dust... that is the reason I had N95 masks already. My dawgs and I track in a lot of dust, to where the vacuum fills 3 times in one session. My environment is always "dirty". And there is a lot ofmold around here. Spray ag is on 3 sides of my property, with whatever they are spraying.
Someone suggested putting one of these in-line on a whip:
I used to have one of those on a car. They are not too big. 20 micron.