AirCleanÂ® Systems ductless fume hoods provide excellent protection for the operator and other employees from toxic fumes and vapors that are generated during experiments in laboratories. Room air is pulled into the hood through the adjustable front sash and allowed to mix with the experiment. The air is pulled up into the bonded carbon and/or HEPA filter bed where either adsorption of fumes and vapors or collection of particulate occurs. (The bonded carbon filter is only for adsorption of fumes and vapors and the HEPA filter is only for collection of particulate). Clean air is then exhausted back into the room through the rear or the top of the fume hood. Real time gas sensor technology (AirSafeâ„¢) ensures protection of the operator and other personnel from exposure to toxic chemical fumes and vapors.