Okay, If you're going to get a mask, get something GOOD. Go for a gas mask or at least a can filter styled mask... The white, cheap, paper mask that are passed off as painting masks only make things worse. My friend and I painted the walls and ceiling leading up to his room, the aerosol cloud was intense, and ventilation was shitty... I'm not sure how many brain cells I lost that day, but the crappy masks didn't help.
We could see paint gathering on the outside of the masks but we could still get huge hits of the fumes, but we thought they were working. Eventually the smell wouldn't go away so we took the masks off and left the area. We saw on each other, that the paint fumes had actually accumulated inside our masks, and it was gathering everywhere. We had blue paint all over the place, and it was gathering up our noses. It wasn't easy getting dried paint out of there, but the next few days my snot was black.
Case in point, if you dont wan to really fuck with someone blowing black snot rockets, then invest in a good mask...