your fan could be pullin to much sucking dirt .most all dirt comes off you and paint cup bottom sitting on bench . air hose in side and outside of the hose. car .you can blow shop out but this can add to more dirt up in the air so if you do this you have to let the shop sit over night . i allways wetted the floor . i painted cars for many years not very many in a real booth the cars i did shoot in them did not come out any cleaner then the many shops i shot paint in with out one