Accession Number : ADA464232


Title :   Viral Penetration of High Efficiency Particulate Air (HEPA) Filters


Descriptive Note : Conference paper


Corporate Author : APPLIED RESEARCH ASSOCIATES INC TYNDALL AFB FL


Personal Author(s) : Helmbuch, Brian K ; Hodge, Jennifer K ; Wander, Joseph D


Full Text : http://www.dtic.mil/dtic/tr/fulltext/u2/a464232.pdf


Report Date : Feb 2007


Pagination or Media Count : 25


Abstract : High Efficiency Particulate Air (HEPA) filters are the primary technology used for particulate removal in many individual and collective protection applications. HEPA filters are commonly thought to be impenetrable to particulate matter, but in fact they are only 99.97% efficient at collecting the most penetrating particle ( 0.2 micrometer). While this is an impressive collection efficiency, HEPA filters may be vulnerable to certain types of threats: Viruses are submicron in size and most have very small minimum infections doses (MID). Therefore, an appropriate viral challenge will yield penetration that exceeds the MID, for many of the threat agent viruses. Nonetheless, the overall particle size (agglomerated viruses and/or viruses attached to inert carriers) will determine the capture efficiency by HEPA filters. Aerosolized viruses are commonly thought to exist as agglomerates, which would increase the particle size and render them more prone to capture. However many of the threat agent viruses can be highly agglomerated and still exist as submicron particles. Furthermore the stability of aggregates is not well understood, and they may break apart during filtration. We have demonstrated in our laboratory that biological aerosols of MS2 coli phage, a common viral simulant, can penetrate both Carbon HEPA Aerosol Canisters (CHAC) and flat sheet HEPA material. The penetration is linear over time, thus viral penetration exceeding the MID is expected to occur in minutes following a viral challenge. We are currently investigating the particle size of the MS2 coli phage aerosol and our aim is to shift the particle size to see what effect it has on penetration. Furthermore, we are evaluating the penetration characteristics of a mammalian virus, which may better represent the threat agent viruses.


Descriptors :   *PARTICULATES , *AIR FILTERS , PARTICLE SIZE , SYMPOSIA , EFFICIENCY , CANISTERS , BIOLOGICAL AEROSOLS , AGGLOMERATES , COLLECTIVE PROTECTION , VIRUSES , INFECTIOUS DISEASES , PENETRATION , DOSAGE


Subject Categories : Pumps, Filters, Pipes, Tubing, Fittings & Vlvs
      Air Pollution and Control


Distribution Statement : APPROVED FOR PUBLIC RELEASE