OSHA defines a filtering facepiece (dust mask) as “a negative pressure particulate respirator with a filter as an integral part of the facepiece or with the entire facepiece composed of the filtering medium.”
A filtering facepiece, e.g. N95 respirator, is typically used for added comfort and protection when particulate contaminant concentrations are below the OSHA permissible exposure limit. In this case, filtering facepiece respirator use is voluntary with only a copy of Appendix D to the OSHA respiratory protection standard required to be provided to the employee. This appendix offers information on the use and limitations of respirators.
There may also be conditions when the employer requires use of filtering facepiece respirators such as in healthcare for protection against infectious micro-organisms. In this case, a complete respiratory protection program is required by OSHA. This includes a written plan, medical evaluation, annual training, annual fit testing of the filtering facepiece, and program evaluation.
For additional information, click on this link to an OSHA Letter of Interpretation that answers seven questions on filtering facepiece use.
For a full summary of OSHA’s respiratory protection program requirements, check out the two part MEMIC Safety Net Blog - What Do I Really Need for a Respiratory Protection Program?