Industrial
Hygiene,
Construction,
and the
Hole in the
Ground
BY EDWARD J. WILLWERTH
OSHA’s long-awaited Notice of Proposed Rulemaking (NPRM) for Confined Spaces in Construction was released for review and com- ment three years ago. Politics, the
economy and resources being what
they’ve been, the January 2008
deadline for comments has been
followed by an unsurprising silence.
The matter has just now resurfaced
on OSHA’s agenda for planned action in 2011.
As we wait, however, it’s worthwhile
considering how this pending change will
affect construction in the U.S. What would
be an appropriate model for forming a
construction industry confined spaces
(CICS) standard, and what would such a
standard mean for industrial hygienists?
Accumulating Risks
I’ve gotten the impression that CS work is
often considered a safety issue rather than
an IH issue. This is a huge misconception.
Consider a tragic fatality that occurred
in the early 1990s. A worker in East
Providence, R.I., was overcome and killed
by toluene (CAS: 50646-98-5) exposure
while cleaning ink from a tank. He was a
trained and experienced contracted tank
cleaner. His company had performed the
same job at the same facility five times
previously, using an array of PPE.
Though this accident happened a few
weeks before OSHA’s general industry
confined spaces, or GICS, standard
(29CFR1910.146–Permit-required confined spaces) went into effect, the cleaning company stated afterward they were
nevertheless trying to conduct the job in
compliance with the pending standard.
The volume of the tank was about 7. 5
m3. As a matter of mechanics, the space
passed through the following stages as
liquid toluene in the ink evaporated into
the tank, slowly poisoning, incapacitating, and eventually killing the cleaner:
• At 0.7 ml evaporated (about 14
drops), the space reached the (now)
current 20 ppm TLV®.
• At 7 ml evaporated, it reached the
(then and still) current 200 ppm PEL.
• At 17 ml evaporated, it reached the
500 ppm IDLH level.
• At 390 ml evaporated, it would have
reached 1.1 percent of toluene’s lower
flammable limit (LFL).
Control vs. Elimination of Hazards
This accident demonstrated a fundamental
flaw in the GICS. As the concentration of
