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New viral disease such as SARS and H1N1 highlighted the vulnerability of healthcare workers to aerosol-transmitted viral infections. This paper was to assess the protection performance of different level personal respiratory protection equipments against viral aerosol. Surgical masks, N95 masks and N99 masks were purchased from the market. The masks were sealed onto the manikin in the aerosol testing chamber. Viral aerosol was generated and then sampled simultaneously before and after the tested mask using biosamplers. This allows a percentage efficiency value to be calculated against test phage SM702 aerosols which surrogates of viral pathogens aerosol. At the same time, the masks face fit factor was determined by TSI8020. The viral aerosol particles aerodynamic diameter was 0.744 μm, and GSD was 1.29. The protection performance of the material of all the tested masks against viral aerosol was all >95 %. All the five surgical masks face fit factor were <8. F model N95 mask and H model N99 mask face fit factor were all >160. G model N95 mask face fit factor was 8.2. The protection performances of N95 or N99 masks were many times higher than surgical mask when considering the face fit factor. Surgical masks cannot offer sufficient protection against the inhalation of viral aerosol because they cannot provide a close face seal. [ABSTRACT FROM AUTHOR]

Hospital-based outbreaks of severe acute respiratory syndrome (SARS) have once again highlighted the vulnerability of healthcare workers (HCWs). Use of personal respiratory protective equipment was the main method used by HCWs to avoid nosocomial transmission. This paper describes the technology used to evaluate the filtration efficiency of the half-face medical protection mask (N99), manufactured by Firmshield Biotechnology, against viral aerosol. Viral aerosol was generated and then sampled simultaneously with and without the test mask. This enables a percentage efficiency value to be calculated against test phage f2 aerosols (surrogates of viral pathogen aerosols). At the same time the mask filtration efficiency against NaCl particle aerosol was determined by use of TSI8130 equipment and face-fit factor was tested by use of TSI8020 equipment. The half-face medical protection mask (N99) evaluated by use of the viral aerosol had a filtration efficiency >99%. The mask filtration efficiency against NaCl particle aerosol was 99.634 ± 0.024% and it had a good face-fit factor. This half-face medical protection mask (N99) can protect the wearer from viral aerosol disease transmission. The test method can be used to assess filtration efficacy against viral aerosol of masks used for respiratory protection. [ABSTRACT FROM AUTHOR]