What is an N95 respirator?

The NIOSH respiratory protection approval regulation (42 CFR 84) defines the term “N95” to refer to a filter class, not a respirator. However, many filtering facepiece respirators have an N95 class filter and many people refer to them, and have come to know them, as N95 respirators. A filtering facepiece respirator that filters out at least 95% of airborne particles during “worse case” testing using a “most-penetrating” sized particle is given a 95 rating.1 There are nine classes of NIOSH-approved particulate filtering respirators available at this time. 95% is the minimal level of filtration that will be approved by NIOSH. The N, R and P designations refer to the filter's oil resistance as described in the table below.

N95, N99, N100 - Filters at least 95%, 99%, 99.97% of airborne particles. Not resistant to oil.

R95, R99, R100 - Filters at least 95%, 99%, 99.97% of airborne particles. Somewhat resistant to oil.

P95, P99, P100 - Filters at least 95%, 99%, 99.97% of airborne particles. Strongly resistant to oil.

All NIOSH-approved filtering facepiece respirators are marked with the manufacturer’s name, the part number (P/N), the protection provided by the filter (e.g., N95, P100), and “NIOSH.” Some filtering facepiece respirators approved by NIOSH may have the NIOSH approval number (TC-84A-xxxx) as an additional identification marking. This information is printed either on the face, exhalation valve (if one exists), or head straps (see Figure 1). The lot number or date of manufacture may appear on the respirator or may be located on the packaging. View a listing of all NIOSH-approved particulate filtering facepiece respirators. NIOSH also maintains a separate database of all NIOSH- approved respirators, inclusive of all respirator types on the Certified Equipment List.

If a particulate filtering facepiece respirator does not have these markings as identified above and does not appear on one of these lists, it has not been certified by NIOSH for occupational use.

Figure 1. Example of typical markings on approved filtering facepiece respirators.

1 Reference: Rengasamy,S.,W.P.King, B.C.Eimer and R.E. Shaffer.(2008). Filtration performance of NIOSH-approved N95 and P100 filtering facepiece respirators against 4 to 30 nanometer-size nanoparticles. Journal of Occupational and Environmental Hygiene 5(9):556-564.