An air cleaner or air purifier is a device which removes contaminants from the air. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating polluted air or second-hand tobacco smoke. Commercial grade air filters 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 are used to reduce the concentration of these airborne contaminants and though very useful for people who suffer from allergies and asthma, technological and scientific studies are finding that poor air quality is more a contributing factor of some forms of cancer, respiratory illnesses, COPD, and other pulmonary infections and illnesses. They also reduce the need for frequent room and area cleaning.
Best Air Cleaners should obviously have a Hepa filter in it. HEPA filters remove at least 99.97% of 0.3-micrometer particles, and are usually more effective for particles which are larger or slightly smaller. They are effective down to 0.01 micrometers in many cases, but become ineffective for particles smaller than 0.01 micrometer[citation needed]. HEPA air purifiers which filter all the air going into a clean room must be arranged so that no air bypasses the HEPA filter. In dusty environments, a HEPA filter may follow an easily cleaned conventional filter (prefilter) which removes coarser impurities so that the HEPA filter needs cleaning or replacing less frequently. HEPA filters do not generate ozone or harmful byproducts.
