1.2.1 N95 Respirator
These require certification by the NIOSH based on filter efficiencies with an assigned protection factor (APF) of 10.(69) They must have less than 5% penetration for aerosol with a mass median aerodynoamic diameter of 0.3 microns.(68) When the air is forced through the filtering material, contaminants are captured, which reduce the exposure to large droplets and small infectious particles in both directions.(67)
The two types are filtering facepiece respirator where the entire facepiece is made of filtering material, or elastomeric respirators that have replaceable filters or cartridges.(67)
Air-purifying respirators are further classified according to the efficiency at which they remove particles (95%, 99% or 100%), and the resistance to oil.(36) N-series are not resistant to oil, R-series are resistant to oil, while P-series are oil proof.(36, 68)
N95 is currently recommended for HCW who work within 2 meters of patients known to be, or suspected of being infected with SARS-CoV-2 and those performing AGP by most institutions (table 1).(10, 70-74)