This vapor mitigation system (VMS) is one of two installed by RAdata at a new HDC (NYC Housing Development Corporation) financed low-income housing apartment building in Brooklyn for indoor air quality. The exhausts are located on the roof and the yellow labels are special decals applied to the roof surface to designate a labeled exhaust safety area for contractors and maintenance staff. There are visual and audible alarms installed to alert maintenance staff if either system requires attention. You can read more about Vapor Mitigation Systems here.
Vapor Mitigation Systems, Rooftop Fan Units, Brooklyn, NY