February 13, 1981
MEMORANDUM FOR: ROGER CLARK
THRU: JOHN B. MILES, JR.
Office of Field Coordination
FROM: BRUCE HILLENBRAND
Federal Compliance and State Programs
SUBJECT: November 4, 1980, Memorandum Requesting an
Interpretation of 29 CFR 1910.1017(b)(5) and
the Definition of "Massive Release" of Vinyl
The term "massive release" applies to a concentration of 100 ppm or higher
of vinyl chloride in the general work area, or the general workroom air. It
refers to an unexpected or uncontrolled release of vinyl chloride; i.e.,
leakage due to equipment failure such as from a relief valve, pipe leak or
process (unit) leak which is considered an emergency.
November 4, 1980
SUBJECT: Interpretation of 1910.1017(b)(5). Definition of
TO: JOHN B. MILES, JR.
Director, Office of Field Coordination
A more detailed explanation of the term "massive release" in the subject
definition is required. CPL 2-2.4 indicates that an unexpected release of
vinyl chloride is "massive" where the concentration of VC is greater than 100
ppm. Was this explanation intended to refer to concentrations of VC in the
general workroom air or in the worker's breathing zone? Or did it include a
location directly at the point of a leak where the VC level would undoubtedly
exceed 100 ppm? If the latter was meant, it would then be incumbent on
employers to report to OSHA practically any unexpected release of this
substance from a piping system, vessel, etc.
We would appreciate your comments in this regard.
Roger A. Clark