Air-purifying vs. Atmosphere-supplying Respirators » Selection Criteria for Particulate Filters

Illustration of good air being separated from bad

Any filters certified under NIOSH's current Part 84 requirements are generally acceptable for negative pressure respiratory protection against all aerosols, mists, fumes, and dusts subject to the filter stated limitations. These filters will be labeled with a letter N, R or P and a number representing the efficiency, 95, 99 or 100.

An exception for usability occurs when a substance specific OSHA standard, e.g. lead, requires a specific filter efficiency. If one of these standards requires a High Efficiency Particulate Air (HEPA) filter to comply with its requirement, the user should select a filter with a labeled efficiency number of 100.