The present disclosure provides an exhaust system for discharging from semiconductor manufacturing equipment a hazardous gas. The exhaust system includes: a main exhaust pipe having a top surface and a bottom surface; a first branch pipe including an upstream end coupled to a source of a gas mixture containing the hazardous gas and a downstream end connected to the main exhaust pipe through the top surface; a second branch pipe including a downstream end connected to the main exhaust pipe through the bottom surface; and a detector configured to detect presence of the hazardous gas in the second branch pipe.