Hepa Filters

The high efficiency particulate air (HEPA) filter has become an indispensable item in the maintenance of biological safety and is also used as a means of preserving cultures from contamination originating in the surrounding air. HEPA filters originated with military requirements for protection against chemical, biological, and radiological warfare agents and to avoid emissions from nuclear weapons production facilities. Everything about these filters was classified “secret” during WWII and for a number of years after the end of the war. When they were declassified and commercial production commenced, many new uses were found in medicine, microelectronics manufacturing, and pharmaceutical production. A thorough understanding of these filters proved to be so important that they stimulated research and development activities that established the science of air filtration on a firm theoretical basis and promoted rapid advances in materials of construction and production methods. The history of their origin and development is an interesting story in itself and helps our understanding of their capabilities and limitations.