While inspecting a building for an LED retrofit we found lighting fixtures that also perform ductwork functions. I have never seen this before. The fixtures predictably are very dusty. Some have ductwork attached and some just vent into the ceiling for return air. Would this be a code issue to leave them like this or should they be separated from the lights while we are doing the project? I could not find anything in the code book prohibit ing it, but I think it is a crazy thing to do.