Air cleaner is a device which removes contaminants from the air in a room. 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 desktop air purifiers are manufactured as either small stand-alone units or larger units that can be affixed to an air handler unit (AHU) or to an HVAC unit found in the medical, industrial, and commercial industries. Air purifiers may also be used in industry to remove impurities such as CO2 from air before processing. Pressure swing adsorbers or other adsorption techniques are typically used for this.for more about air purifiers.
Air filters utilize fine sieves that filter particles from circulating air. As air flows into the air purifier, the finer the sieve used, the smaller the particles it traps. The accepted benchmark for air filters has been set by the High Efficiency Particulate Air (HEPA) filters, which are guaranteed to trap 99.97% of airborne particles larger than 0.3 microns. Microns are the standard unit used for measuring air particles. Each micron is equivalent to 1/25,400 of an inch. The naked eye cannot see anything smaller than 10 microns, so pollutants like bacteria and viruses escape detection. Room air conditioner filters only capture particles 10.0 microns or larger. HEPA filters remove smaller allergens like dust, smoke, chemicals, asbestos, pollen, and pet dander.