5 feet of tubing. The opening is right next to the tip. Just no vacuum for anything to go in. The fumes just pass by. I assume it needs to be at least enough so that if I cover the nozzle with my finger, I should be able to feel something.
I'm not sure what you want me to say about particulate percentage because that just sounds like an idealistic parameter that would be available in a perfect world where all variables were known. As it is, there's no way for me to measure or even gauge that.