What do the NIOSH ratings on the respirator packages mean?
The National Institute for Occupational Safety and Health (NIOSH) is the U.S. Department of Health and Human Services agency responsible for providing research, information, education, and training in the occupational health and safety fields. The following chart from the NIOSH website describes the various disposable respirator designations. If the respirator is fluid resistant it is addressed separately on the package label or in the technical literature. The filtration rating designation category in the chart is determined by the NIOSH disposable respirator certification test utilizing a 20 minute challenge with 0.3 micron salt particles.