How Does Air Purification Work?
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Air is often purified using what is termed a HEPA filter. HEPA, meaning high efficiency particulate air, is a type of mechanical filter that traps very small particles including dust and microorganisms into microscopic pores. For a filter to be a true HEPA filter it must be able to trap 99.97% of the particles larger than 0.3 microns in size, as stated by the Asmtha and Allergy Foundation or AAF.
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Electronic filters use an electrical charge to attract allergens and other irritants to them and thus clean the air. They are effective to a degree, but do not reduce the amount of odors in the air. Hybrid filters are a combination of electronic and HEPA filter systems. There are also gas phase filters which reduce the amount of odors like cooking smoke, from the air by trapping them. It may not be effective for smaller molecules like formaldehyde or carbon monoxide. Also they do not remove dust or other pollutions and the filters have to be changes relatively frequently, according to the AAF.
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It is important to note that many air filtration systems either create ozone (O3) or ozone byproducts. Electronic filters such as air cleaners that use ions, create small concentrations of ozone that are not necessarily harmful. It is important to note that any filter that specifically claims to clean indoor air by specifically creating ozone is not EPA approved.
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According to the EPA, ozone generating filtration systems wrongfully claim to safely clean the air. The unstable third oxygen in ozone reacts with other airborne chemicals, thereby removing them. Although some filters may react to various degrees with airborne pollutants, ozone reacts with chemicals inside as well as those outside the body. Health problems resulting from these reactions including breathing difficulties, coughing and other respiratory issues even in health individuals. Such generators, at times labeled as "pure air" or " energized air," should be avoided.
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A relatively newer technology called photocatalytic oxidation that has started to be applied to air purification. Using this method, air is cleaned by the conversion of pollutants to harmless compounds like carbon dioxide, water and nitrogen. This is achieved by the catalytic conversion of unhealthy substances via exposure to ultraviolet light, according to makers of AIRLIFE. A similar process occurs in cars in their catalytic converters in order to reduce pollution. AIRLIFE and AirPura are two systems utilizing this technology.
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Cakes
Oct 19, 2009
photocatalytic conversion. it's UV light is likely to be dangerous to the human eye and some UV-C can even kill people. UV-C is (also) used to sterilize food or water. it simply is so good at penetrating flesh that it kills the bacteria by "burning", same as it can give a sunburn. the bacteria's corpse is comprised of protein (nitrogen), carbon and residual water/vapor. re it's similarity to a car's catalytic converter, it is same only inasmuch as each funnels material past an ignition source.
