The Certified Medik-Aire® HEPA filter attachment consists of over 1000 square inches of Certified High Alpha HEPA. This state of the art HEPA filter is rated at 100 CFM and uses the latest technology to provide the best possible filtration without reducing air-flow and the over all cleaning. HEPA (high efficiency particulate air) filters are the highest efficiency filter available for filtration of small particles. Defined by the Institute of Environmental Science, a Certified High Alpha filter must capture a minimum of 99.97% of contaminants at 0.3 micron in size. The first HEPA filters were developed in the 1940's by the Atomic Energy  Commission to full-fill atop-secret need for an efficient, effective way to filter radioactive contaminants. They were needed as part of the Manhattan Project, which was the development of the atomic bomb. HEPA filter technology was declassified after World War 2 and allowed for commercial use. HEPA filters have been traditionally used in hospital operating and isolation rooms, pharmaceutical and computer chip manufacturing, and other application requiring "absolute" filtration. Today certified HEPA filters are used in a wide variety of critical filtration application in the nuclear, electronic, aerospace, pharmaceutical and medical fields, and in equipment for asbestos abatement. HEPA filters are highly recommended for allergy sufferers. $229.00 MSRP