#	Letters of Interpretation
1	11/12/2021 - 1910.146(b) - Permit Required Confined Space Isolation
2	07/17/2014 - 1910.146(b) - Permit-Required Confined Space Entry Requirements For IDLH and Non-IDLH Spaces
3	12/02/2005 - 1910.146(b) - Clarification of "potential atmospheric hazard" when reclassifying a PRCS as a non-permit required confined space.
4	12/02/2002 - 1910.146(b) - Applicability of the confined-space standard to dock-leveler pits.
5	10/20/1999 - 1910.146(b) - PRCS entry: the term "body" includes all extremities.
6	03/26/1999 - 1910.146(b) - A confined space atmosphere above a PEL is not always a "hazardous atmosphere".
7	02/23/1999 - 1910.146(b) - Applicability of 1910.146 to fall hazards into pits.
8	10/27/1995 - 1910.146(b) - Guidance in determining whether elevator pits meet the definition of confined spaces.
9	06/22/1995 - 1910.146(b) - Explanation from OSHA of the "not designed for continuous human occupancy" component if the definition of the term "confined space".
10	11/15/1993 - 1910.146(b) - Permit-Required Confined Spaces: metal container curing ovens.