There are many different methods of filtering air; however, the goal of each is to remove the undesired particulates from the targeted environment. Accordingly, air filtration systems are often added to buildings, rooms, car cabins, airplane cabins, and hospitals for this exact purpose. In general, air filtration systems employ either some kind of fibrous or porous membrane through which the flow of air is passed to remove dust, mites, pollen, bacteria, and most viruses. Another common method is air ionization — in this method a static electrical charge is passed through a conductive medium which then attracts dust particles towards it, trapping them. This method, of course, is far less effective in removing bacteria, mites, and/or viruses from the air.
Air filtration devices can be portable or built into an enclosed structure or passenger cabin. For example, most homes air conditioning systems include an air filter port. This is for two reasons: firstly, the removal of large particulates like dust and pollen can significantly improve the efficiency (and longevity) of the mechanical function of the air conditioner itself; secondly, it also allows the occupant to insert filters with a higher filtration level to also filter out additional undesired particulates. This has become such a commonly utilized feature by allergy sufferers and immunosuppressed individuals that cabin filters have become commonplace in vehicles as well over the past 20 years. Filters that include an absorbent material, such as charcoal (carbon), can also remove many orders or gaseous pollutants from the air.
Hospitals have long employed what are referred to as High-Efficiency Particulate Air (HEPA) filters for patient, staff, and visitor safety. HEPA is a standard that qualifies the ability of the filter to safely and efficiently arrest or remove the presence of dust, pollen, mites, bacteria, and/or viruses down to a specific micron level. HEPA filters must also satisfy quality standards set by the United States Department of Energy (DOE) that the filter removes 99.97% of particulates whose diameter is greater than, or equal to, .3 μm. The particular advantage for this standard in medical environments is that it would filter out potentially dangerous airborne pathogens such as tuberculosis or the chickenpox virus.
The last consideration when looking at an air filtration system is whether it creates negative air pressure, or not. For example, an air filtration system placed in a building's air conditioning system maintains neutral air pressure within the building by pulling in fresh air from outside and porting any exhaust outside the build. Stand-alone portable devices typically are only capable of circulating air within an enclosed area. And, portable air conditioners that pull in outside air, but do not port out exhaust outside will create negative air pressure, promoting unfiltered outside air to seep inside. This largely defeats the entire purpose behind filtering the air.
For more information, contact an air filtration service.