Collective Protection Factors Methodology Development Using High Concentration Polydisperse Inert Aerosols: Results of FY09 Testing.

摘要

Collective protection shelters, designed to remove airborne particles using positive-pressure high-efficiency particulate air (HEPA) filtration, are available in various sizes, shapes, and rigidity. A methodology was developed to establish a test protocol for the measurement of protection factors (PFs) in excess of 5,000,000. Two inert polydisperse aerosols were used under static conditions as surrogates for the smaller submicron virus, toxic industrial chemicals, toxic industrial materials, and the larger micron-sized spore and spore clusters. Polyalphaolefin oil at 0.528 micron mass median aerodynamic diameter (MMAD) and sodium fluorcscein dye at 2.4 micron MMAD were disseminated using an industry standard ATI-TDA-4B generator and SUl A Spray Systems nozzles, respectively. PFs of 77,000 and 250,000 were achieved using a single HEPA-protected shelter, and they could be enhanced in excess of 246,000 and 5,000,000 using a second in-line installed HEPA. Although the dual HEPA- protected shelter results were based on a lower limit of detection of the instrumentation, several orders of magnitude of protection enhancement are likely, given the availability of appropriate instrumentation and sensitivity. As the PF is a function of particle size, the use of monodisperscd aerosols is a logical, though challenging, extension to shelter paniculate penetration.