An N95 mask or N95 respirator is a particulate-filtering facepiece respirator that meets the U.S. National Institute for Occupational Safety and Health (NIOSH) N95 classification of air filtration, meaning that it filters at least 95% of airborne particles. This standard does not require that the respirator be resistant to oil; another standard, P95, adds that requirement. The N95 type is the most common particulate-filtering facepiece respirator. It is an example of a mechanical filter respirator, which provides protection against particulates but not against gases or vapors.
N95 respirators are considered functionally equivalent to certain respirators regulated under non-U.S. jurisdictions, such as FFP2 respirators of the European Union and KN95 respirators of China. However, slightly different criteria are used to certify their performance, such as the filter efficiency, test agent and flow rate, and permissible pressure drop.
The N95 mask requires a fine mesh of synthetic polymer fibers, specifically a nonwoven polypropylene fabric. It is produced by melt blowing and forms the inner filtration layer that filters out hazardous particles.