Hey Denny...
While I am not an expert, I'd strongly suggest excellent breathing protection (including a proper mask and outside oxygen supply) if you are spraying paints like 2 part polyurethanes.
When I was employed by Canadian Airlines they used a two part polyurethane paint that is very common in the painting of planes, cars and even boats and when I took a dangerous goods material handling course on it I learned that ANY exposure for even a short time can result in a cyanide sensitivity problem in later life that CAN kill you. All our painters used excessive breathing protection for this reason.
As it turns out breathing the fumes from this paint (which contains sodium cyanide) damages your body to the point that even breathing a few parts per million years later can do you in for good (if the course was to be believed)
Better to err on the side of caution and better to be safe than sorry... Good luck...
~Trev
