This article introduces the classification method of airborne molecular contaminants (AMC) in cleanrooms based on SEMI standard F21-95, detailing the four categories of gas-phase pollutants and their characteristics. Techniques for controlling odors and gas pollutants include shielding, combustion, ventilation, and removal, with chemical filters removing molecular pollutants through adsorption and absorption principles. Physical adsorption and chemical adsorption are common methods for gas pollutant removal. Selecting appropriate adsorption materials and controlling temperature and humidity are key factors in achieving efficient gas pollutant removal. The activity, size, and surface chemistry of carbon are critical parameters affecting adsorption efficiency. Lastly, three available filtration systems for providing AMC removal are mentioned.