Elastomeric respirator in the context of Mechanical filter (respirator)

An N95 respirator is a disposable filtering facepiece respirator or reusable elastomeric respirator filter that meets the U.S. National Institute for Occupational Safety and Health (NIOSH) N95 standard of air filtration, filtering at least 95% of airborne particles that have a mass median aerodynamic diameter of 0.3 micrometers under 42 CFR 84, effective July 1995.

A surgical N95 is also rated against fluids, and is regulated by the US Food and Drug Administration under 21 CFR 878.4040, in addition to NIOSH 42 CFR 84. 42 CFR 84, the federal standard which the N95 is part of, was created to address shortcomings in the prior United States Bureau of Mines respirator testing standards, as well as tuberculosis outbreaks, caused by the HIV/AIDS epidemic in the United States. Since then, N95 respirator has continued to be used as a source control measure in various pandemics that have been experienced in the United States and Canada, including the 2009 swine flu and the COVID-19 pandemic, and has been recommended by the EPA for protection against wildfire smoke.

The European respirator standards refer to the filtering classification by EN 149, EN 14683, and EN 143, all European standards of testing and marking requirements for respirators. FFP standard masks (where FFP stands for filtering facepiece) cover the nose, mouth and chin and may have inhalation and/or exhalation valves.

EN 149 defines three classes of such particle half masks, called FFP1, FFP2 and FFP3, according to their filtering efficiency. It also classifies masks into "single shift use only" (not re-usable, marked NR) or "re-usable (more than one shift)" (marked R), while an additional marking letter D indicates that a mask has passed an optional clogging test using dolomite dust. Such mechanical filter respirators protect against the inhalation of particulates such as dust particles, droplets, and aerosols. EN 14683 defines respirators for use in medical settings, while European standard EN 143 defines the 'P' classes of particle filters that can be attached to a face mask, which are P1, P2, and P3. The EN 143 filters are typically used on reusable respirators, like elastomeric respirators.

A respirator is type of mask designed to protect the wearer from inhaling hazardous atmospheres including lead fumes, vapors, gases and particulate matter such as dusts and airborne pathogens such as viruses. There are two main categories of respirators: the air-purifying respirator, in which respirable air is obtained by filtering a contaminated atmosphere, and the air-supplied respirator, in which an alternate supply of breathable air is delivered. Within each category, different techniques are employed to reduce or eliminate noxious airborne contaminants.

Air-purifying respirators range from relatively inexpensive, single-use, disposable face masks, known as filtering facepiece respirators, reusable models with replaceable cartridges called elastomeric respirators, to powered air-purifying respirators (PAPR), which use a pump or fan to constantly move air through a filter and supply purified air into a mask, helmet or hood.