【正文】 eed an air purifier primarily for odor and/or gas control, youmost likely want to look for an air purifier that will remove the majority of the particulates first by using a prefilter, then have the gases and odors removedin thegas filter section. Gas molecules arequite smalland usuallycannot be removed by even the finest Hepa filter. These moleculesare microns and smaller. Therefore, they need to be removed physically by a substance or media that will trap these particlesinwhat we call micropores. A good monly used substance is: Activated Carbon. This Activated Carbon is treated by super heating and steaming whichresults in millions of tiny pores. Each one of these pores will be able to adsorb the gas molecules. Once these microporesare unable toabsorb any more of the gas molecules,they are said to be saturated. This meansthey will not be able to adsorb gases and odors with any degree of efficiency any longer. Another method of gas and/or odor removal is through the process of chemical absorption. This iswhena gas moleculeis exposed to a chemical agentin bination with water molecule causing a chemical reactionto occur whereby the resultinggas moleculeis broken down into a harmless byproduct such as carbon dioxide and/or water.Commonly substances such as alumina silicate, alumina oxide, and potassium permanganate are used in this process. These are particularly effective at removingthe gases of lighter molecular weight such as formaldehyde.Regarding the Size and Quality of the Hepa filters in current dayAir Purifiers.The more square feet of Hepa filter media there is in an air purifier, the more particulate matter will be removed from the air before it bees clogged. Also the air purifier will be able to remove more particulates with each pass. The quality of the Hepa filter is very important both in the material used and the design. The pleats of a Hepa filter need to be uniform so each one has the same efficiency of filtration. If the pleats are too close together they can restrict the air movementthus resulting in a loss of airflow. Some Hepa filters out there use synthetic materialsrather than the traditional paper. Thin paper is usually the best material because it39。s both effective at removing the highest percentage of the microscopic particulatesyet it doesnot adversely restrict theairflow. The better quality grades of Hepa filters are extremely delicate andare easily damaged. This is why the air purifier panies that are of better quality will house the filter in such a way as to protect the actual Hepa filter material.Particlate Matter that causes Lung Damage:Particulate matter that causes Lung damage isof most concern becausethese particulatesare small enough to get throughsinus cavities and intorespiratory systems while at the same time they are largeto the point of not being able tobe exhaled. It ismost important when consideringthe purchase of an air cleaner to make sure that the product will be able to filter all of the dangerous offending particulate matter from the treated air. The size of these particulates range willfrom 9 microns to of a micron in size. This is whyHepa filtration productshave bee such an important aspect of the air cleaning industry.Particulates which cause lung damage fall into the same size range as dosome bacteria, most molds, fumes, smoke, smog, diesel exhaust, cat allergens, pollen fragments, house dust mite allergens, settling dust, and suspended atmospheric dust. All of these particulates can cause an allergic reaction.Bear in mind thatit is still necessary to filter out particulate matter which issmaller than this, however, particulates smaller than microns have a better chance of being exhaledfrom withinyour respiratory system. Somedamage causing particulate matterwill still remain in your lungs. The American Lung Association believes that particulates that have been treated with a high level ofionization have a higher likelihoodof sticking to certain parts of your respiratory system if inhaled so their likelihood of being exhausted from the respiratory systemis low. The air cleaner抯 ability to filter out particulates in the to of a micron range in size is considered important since this would also includecertain bacteria, viruses,pet dander,house dust mite allergens, as well assmoke and smog.Are UltraViolet Light Air Purifier Systems Effective?Ultraviolet [UV] lighthasbeen a provenmethod knownto the medical munityas a highlyeffective way to sterilize air. By killing germs, bacteria, mold, viruses, and other microorganisms, UV has been shown to be a reliable method of sterilization. However, these results are usually achieved in acontrolled environment. For example, if a surfacecontaining germsis directly exposed to UV light of sufficient intensity (dosage) and of the proper frequency for apredetermined period of time (exposure), the surface will be sterilized.The difficultly is attaining the required level ofcontrol needed to sterilize microorganisms in an air purifier. The biggestdifficultywith regard to exposure to UV light in an air purifier is when the micro organisms are moving through the air purifier at a fairly high rate of speed because ofa fan. The question is: are the contaminantsexposed to the rays of the UV light long enough to alter the DNA and the RNA of the micro organisms which is necessary to sterilize the air?The lower the fan speed the higher the efficiency of sterilization of micro organisms. Some products feature a hybrid approach, that is they have a UV light that bathes the Hepa filter with continuous light which in theory will killthe micro organisms that have been trapped by the Hepa filter. This means that the Hepa