Effectiveness of Three Decontamination Treatments Against Influenza Virus Applied to Filtering Facepiece Respirators

Single-use filtering facepiece respirators (FFRs) are effective precautions against airborne pathogenic microorganisms; however, during pandemics the demand for FFRs may far exceed availability. Reuse of FFRs following decontamination has been suggested but few studies to date have addressed the feasibility. Concerns regarding biocidal efficacy, filter performance post decontamination and cost of decontamination may affect the adoption of reuse measures. This study examined the effectiveness of three energetic decontamination methods (ultraviolet germicidal irradiation, microwave-generated steam and moist heat) on two NIOSH certified N95 FFRs contaminated with H5N1. An aerosol settling chamber was used to apply virus-laden droplets to FFRs in a method designed to simulate respiratory droplet deposition of viruses onto surfaces. Results differed based on the method used for detection of the virus. When the FFRs were examined post decontamination by virus culture, all three decontamination methods worked equally well and reduced virus load by 4 log TCID50. Analysis of the treated FFRs using a quantitative molecular amplification assay (qRT-PCR) indicated that the UVGI decontamination method provided lower levels of detectable genome copies than the other two methods. Filter performance was evaluated before and after decontamination using a 1% NaCl aerosol. All FFRs displayed penetration below 5% at the 300- nm particle size. No reduction in filtration performance was found in FFRs that had been exposed to virus and subsequently decontaminated. These findings indicate that, when properly implemented, decontamination methods are effective for FFRs and do not affect their filtering function; however, other factors may affect the decision to re-use FFRs. Published in The Annals of Occupational Hygiene, 2011.