HEPA and ionic air filters are used in buildings and homes to reduce the dust load, remove allergens from the air as well as pet dander. The HEPA filters draw air through a thick filter and return it to the room through the back or the top. Ionic air filters emit ions into the air that render the dust and particulates in a room inactive and they fall to the floor or deposit themselves on furniture or walls.
History of Air Filters
HEPA filters were invented in the 1940s to filter the air while scientists were developing the atom bomb for the Manhattan Project. The filters were used to assure that the air in the laboratories would be almost 100 percent free of dust and particulates. After the war was over, the technology to make the filters was declassified and over the years, the technology has improved; today's HEPA filters are much smaller than the early filters.
Ionic generating filters were developed in 1974 when meteorologists in Switzerland researched the relationship between strong winds and plant and animal distress. They correlated a high concentration of positive ions with human discomfort, after which engineers found a way to create negative ions using electricity to counteract the damage from positive ions.
How a HEPA Filter Works
HEPA filters work by sucking air through a filter that removes particles as small as 3 microns. HEPA air cleaners come with outer filters to preserve the life of the HEPA filter, which can be almost as expensive to replace as buying the HEPA filter originally. The outer filters can be carbon or foam and are washable. The HEPA filter uses a fan to pull air through it and it puts the filtered air back into the room to reduce dust, pollen and dander.
How Ionic Filters Work
Ionic filters emit negative ions that neutralize the positive ions in a room. The particulates eventually fall to the floor or settle on surfaces like walls and furniture unless there is a filter and a fan associated with the ionic filters to blow the air through, in which case they trap the particles on the filters which can be removed and cleaned.
Advantages/Disadvantages of HEPA Filters
HEPA filters are used in clean rooms, operating rooms, airplanes, and homes where people need relief from allergies or have lung problems. The HEPA filters are highly effective at removing air borne pollutants. Disadvantages include the cost of operation, filter replacement and the noise generated by their fans.
Advantages/Disadvantages of Ionic Filters
Ionic filters do not take up much space, are quieter and less expensive to operate than HEPA fans. The ionic filters create ozone, however, which is a detractor for using them. The EPA discourages people from using ion filters or ozone filters in their homes because ozone could reach unsafe levels and cause long term throat and lung damage.
- Photo Credit saw dust image by Wolfgang Zintl from Fotolia.com
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