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The first HEPA
filter (high efficiency particulate air) was designed in the
1940's by the research and development firm Arthur D. Little
under a classified government contract as part of the
Manhattan Project during World War II. The HEPA filter
solved a critical life threating problem, the need to
control very small nuclear radioactive particles which were
floating around the labs.
Having
identified 0.3 micron size particles as the most penetrating
size particle and representative of the radioactive
particle, 0.3 microns was established as the particle size
which filter efficiency performance was to be determined.
That is why "true" HEPA filters must remove 99.7% of all
particles 0.3 microns and larger.
The generic
acronym HEPA came into use some time dusring 1950 when the
filter was commercialized and the original term became a
registered tradename.
Over the next
50 years, HEPA filtration has gradually evolved as
technological breakthroughs in aerospace, pharmaceutical
processing, photographic film manufacturing, data processing
and microcircuitry demanded higher and higher levels of air
cleanliness. If not for HEPA filtration, such advances as
the lunar landing and the introduction of the silicon chip
might not have been achieved and adequate control of
hazardous and toxic particulate would not be possible.
HEPA filters
are made of fine-diameter fiberglass compressed into a
fabric-paper sheet, which is then finely pleated to increase
the particle-trapping surface area. HEPA filter standards
are set by the US Department of Energy (DOE) which maintains
strict testing requirements.
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