Assessment the protection performance of different level personal respiratory protection masks against viral aerosol

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.