Ventilation control efficiency of air pollutant emitted from a type P5000 metal etcher (Applied Materials, Inc.) during preventive maintenance was investigated in this study. Sulfur hexafluoride (SF6) gas of 1000 ppm was released at different flow rates at the bottom of the chamber to simulate the emission. When a large flow rate of 3130 L/min was vented from the venting port near the top of the chamber, the control efficiency of air pollutant is nearly 100%, whether the top of the chamber was open or enclosed with a specially-designed cover. The SF6 concentration at the breathing zone was found to be lower than the detection limit of the FTIR spectrometer. Numerical simulation of the flow and pollutant concentration fields yielded control efficiencies in good agreement with the experimental data. When the chamber was open, the control efficiency remained at 100% if the venting flow rate was greater than 1200 L/min; while the control efficiency decreased with decreasing flow rate. In comparison, the control efficiency with the specially-designed cover, which had a much smaller opening, was 100% for venting flow rates as low as 31.3 L/min.