Filtration Performance of FDA-Cleared Surgical Masks.

Ashortage of NIOSH-approved respirators is predicted during an influenza pandemic and other infectious disease outbreaks. Healthcare workers may use surgical masks instead of respirators due to non-availability and for economical reasons. This study investigated the filtration performance of surgical masks for a wide size range of submicron particles including the sizes of many viruses. Five models of FDA-cleared surgical masks were tested for room air particle penetrations at constant and cyclic flow conditions. Penetrations of polydisperse NaCl aerosols (75±20 nm, count median diameter), monodisperse NaCl aerosols (20-400 nm range) and particles in the 20-1000 nm range were measured at 30 and 85 liters/min. Filtration performance of surgical masks varied widely for room air particles at constant flow and correlated with the penetration levels measured under cyclic flow conditions. Room air particle penetration levels were comparable to polydisperse and monodisperse aerosol penetrations at 30 and 85 liters/minute. Filtration performance of FDA-cleared surgical masks varied widely for room air particles, and monodisperse and polydisperse aerosols. The results suggest that not all FDA-cleared surgical masks will provide similar levels of protection to wearers against infectious aerosols in the size range of many viruses.