A disposable N95 mask (respirator) is a safety device that covers the nose and mouth and helps protect the wearer from breathing in some hazardous substances. An N95 mask protects you from breathing in small particles in the air such as dust and mold.
The “N95” is one of three types of filters – N, R and P. These refer to the type of resistance they have to the degrading of their filtering efficiency when exposed to different kinds of airborne particulates, mists, etc. To help people remember which filters can be used for protection against different kinds of airborne particulates (e.g., dust, fume and mist). NIOSH provides the following guide:
N – Not resistant to oil
R – Somewhat Resistant to oil
P – Strongly resistant to oil (oil Proof)
The “95” in N95 refers to the filter efficiency. There are three levels of filter efficiencies – 95% (N95), 99% (N99), and 99.97% (N100 or HEPA filter) tested against aerosol (fine mist) droplets 0.3 microns in diameter. N95 type respirators are the respirators recommended by the Government of Canada and the U.S. Centers for Disease Control and Prevention (CDC) for use by health care workers in contact with patients with infections that are transmitted from inhaling airborne droplets (e.g., tuberculosis (TB); also recommended for health care staff working with patients having or suspected of having SARS, severe acute respiratory syndrome).
High risk procedures such as bronchoscopy and autopsy require additional protection. For example, protection may include full facepiece negative-pressure respirator, powered air-purifying respirators, and positive pressure airline respirators equipped with a half-mask or full facepiece. A supplied-air respirator with a hood may be needed for staff who cannot be properly fitted with respirators with a facepiece. In medical procedures that generate aerosol mists, goggles or face shields (with safety glasses or goggles) should also be used to prevent eye contamination.