An air purifier or air filter may be a device which removes contaminants from the air during a room to enhance indoor air quality. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating second-hand tobacco smoke. The commercially graded air purifiers are manufactured as either small stand-alone units or larger units which will be affixed to an air handler unit (AHU) or to an HVAC unit found within the medical, industrial, and commercial industries. Air purifiers can also be utilized in industry to get rid of impurities from air before processing. Pressure swing adsorbers or other adsorption techniques are typically used for this.