SN 68 - Use of Non-NIOSH Approved Respirators for Voluntary Use

As described in this Standards Notice, non-NIOSH approved respirators, although not recommended by the OSH Division, are acceptable for voluntary use when the criteria set forth in 29 CFR 1910.134(c)(2) have been satisfied. 

Also reference Field Operations Manual Chapter 15: Industrial Hygiene Compliance, CPL 02-00-158, Inspection Procedures for the Respiratory Protection Standard, 29 CFR 1910.134, OPN 127 - Respirator Use Policy under the Cotton Dust Standard,  SN 55 - Facial Hair and Respirator Use, and  SN 63 Requirements for Workers Who Are Actively Conducting Operations in IDLH Atmospheres.  Additional information and resources can be found on the safety and health topic page for Respiratory Protection.