Abstract: A ventilation system is provided in an automobile by forming an intake opening in the top of the seats in the automobile. A telescopic pipe is located in the cushion of the seat with its top end mounted to the intake opening and its lower end mounted to an outlet port at the underside of the seat. An ammonia sensor and a air drawing fan is mounted in the telescopic pipe. The air drawing fan is actuated by the ammonia sensor with the control of a seat fan module when the ammonia sensor detects body waste odor air expelled by a passenger sitting in the seat. Exhaust ducts are provided for conducting the odor air out of the automobile.