N95 Respirators Filtering half-mask respirators, also called filtering facepiece respirators (FFRs), are the most commonly used respiratory protection in healthcare. FFRs are devices designed to fit around the user’s nose and mouth, creating an airtight seal with the face. these filters bear the N95 designation to indicate they are not resistant to oil or solvents (N) and that they are intended to filtrate at least 95% of airborne particles >0.3 μm in size. N95 filters are made of several layers of woven synthetic material treated to sustain an electrostatic charge. In addition to creating a mechanical barrier against aerosols, N95 filters retain charged particles, such as bacteria. In the healthcare setting, N95 filters provide adequate protection from most airborne pathogens.