in the fabrication of semiconductor integrated circuits , a ventilation system is disclosed which includes a sleeve device , a ventilator and a sensor . the sleeve device has at least one aperture thereon for gas transfer . the ventilator is coupled to the sleeve device . the sensor is coupled to the sleeve device . a method of ventilation is also disclosed , which includes a step of sensing a relative movement between a sleeve having at least aperture for gas transfer and a gas outlet connected to a pipeline , and a step of generating a signal to control a ventilator when the relative movement between the sleeve and the gas outlet is sensed .