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Alice Hamilton Awards: Research Updates for 2012 - Engineering and Controls

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Edward Fisher, Jessica Williams, & Ronald Shaffer

Evaluation of microwave steam bags for the decontamination of filtering facepiece respirators

NIOSH-certified N95 Filtering Facepiece Respirators (FFRs) are an important non-pharmaceutical intervention to reduce exposure to airborne respiratory pathogens. In 2006, the Institute of Medicine (IOM) issued a report which identified three criteria for assessing FFR biological decontamination methods: the method must remove the viral threat, be harmless to the user, and not compromise the integrity of the FFR. When the report was issued, no published data was available on decontamination of FFRs. To address this gap, NIOSH began a research effort ( to understand the efficacy and impact of FFR decontamination and the risks associated with handling an FFR contaminated by virus particles. This project was completed in 2012, resulting in 15 publications in peer-reviewed journals and served as the basis for two American Society for Testing and Materials (ASTM) test methods on contamination and decontamination of surfaces and different types of materials, including textiles and personal protective equipment (PPE).

One of the manuscripts from the FFR reuse project titled "Evaluation of microwave steam bags for the decontamination of filtering facepiece respirators" received the 2012 NIOSH Alice Hamilton Award in the Engineering and Controls category. This manuscript discussed the application of an accessible and practical decontamination technology suitable for use by the general public, while addressing knowledge gaps identified during the course of the FFR reuse project. Microwave steam bags, used for home decontamination of infant feeding accessories, are available for purchase in many retail stores. The instructions are written for the general public and are based on the operation of a microwave oven. This is in contrast to previously examined decontamination methods which required complex equipment and training such as chemical decontamination, ultraviolet germicidal irradiation lamps, vaporous hydrogen peroxide generators, and incubators.

Although the use of microwave steam bags may provide a mechanism to effectively decontaminate FFRs, this method and other viable decontamination procedures have yet to be adopted into practice. One important piece of missing information is quantitative data on actual FFR contamination levels experienced by a health care worker during close contact with infectious patients. In 2011, NIOSH initiated a research project titled "Why Hospital Staff Catch the Flu: Assessing Modes of Transmission" to, in part, address this data gap. This current project ( seeks to improve understanding of the relative contributions of the direct-contact (e.g., fomite), aerosol, and direct-spray transmission routes of influenza in healthcare settings. Recently completed laboratory studies examined the relationship of airborne influenza concentration to levels of PPE contamination. Field studies are underway at Johns Hopkins University to measure influenza exposures and PPE contamination resulting from routine patient care.

  • Page last reviewed: April 26, 2013
  • Page last updated: April 26, 2013
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