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ter the fresh air system of the proved cartridge respirator 5. After cessation of spraying, no
building. with a prefilter. person may enter the 50 foot zone
(e) Tempered makeup air is recom b) In spaces smaller than 2,500 or the enclosed space for at least
mended to avoid building nega square feet, all persons who 30 minutes unless wearing an ap
tive pressure and to improve enter the space must wear ap proved chemical cartridge respir
general room ventilation. proved air-supply respirators. ator, or unless mechanical venti
(f) In some cases, the process equip 4. The respirator air supply must be lation has been employed to
ment at which diisocyanate leaks from a source maintained and lo insure that isocyanate concentra
may occur is too extensive to be cated to provide clean respirable tions are reduced to levels below
enclosed by an exhaust hood. air.
In this event, mechanical exhaust
and supply ventilation of the en- —
tire room may be necessary.
(g) The exhaust systems should be
periodically cheeked to insure .<
their proper operation.
Construction and Insulating-1 n-Ptace
—Investigations conducted in both in
door and outdoor locations show that
there can be a serious isocyanate vapor
hazard not only to the insulating work
ers but to other workers who may be
in the vicinity. Those who follow the
insulators on the job can be affected—
the carpenters, electricians, and other
tradesmen. In an effort to control the
insulation workers’ exposure and mini
mize the hazard to others, our Occupa
tional Health Division, in cooperation
with representatives of the insulating
workers, contractors, and isocyanate
manufacturers, has developed certain
safeguards.
Spraying:
1. The spray operator and his helper
must wear an approved air-supply
respirator.
2. All other persons located within
50 feet of the sprayer must wear
approved air-supply respirators.
3. a) In spaces larger than 2,500
square feet and out-of-doors,
persons who enter the 50 foot
zone only intermittently or
temporarily must wear an ap Well Baffjed Hood fer Mold Kelecsse Spraying
Figure 5
Isocyanate Samples
Number of Maximum
Calendar Industries Number of Concentration Number of Samples at Indicated Concentrations, PPM
Year Investigated Studies Samples Found = <.005 >.005-. 01 >.01-.015 >.015-.02 >.02-. 025 = >.026
1959 3 3 22 0.10 17 1 2 2
1960 2 2 11 0.30 2 3 1 1 4
1961 2 3 14 0.03 11 2 1
1962 6 8 34 0.83 17 2 1 1 2 11
1963 4 4 25 0.004 11 2 4 1 1 6
1964 14 22 100 . 0.11 48 10 1 8 1 32
1965 10 13 85 0.10 49 15 10 4 2 5
1966 7 14 105 0.80 52 12 6 5 6 24
1967 4 5 31 0.03 14 13 2 1 14
1968 13 21 112 0.28 59 10 5 5 2 31
1969 14 19 116 0.07 90 5 4 7 3 7
Total i 114 665
