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)