Cooking fume is a large amount of thermal oxidation decomposition products produced by cooking oil and food under high-temperature conditions. Filters are not effective against these gases, partly because of their small particle size. Odor removal requires the use of gas-phase filtration media such as activated carbon, which utilizes the pore structure and surface area to absorb the odors. Because surface area and pore structure are critical, filtration solutions must remove all grease and mist before the exhaust air contacts the gas-phase media, to prevent the grease and mist to stick onto the activated carbon media. Otherwise, the media will be rendered useless and can become a fire hazard.