Methyl isocyanate liquid and vapor permeation through selected respirator diaphragms and chemical protective clothing.

Initially, a study was undertaken to evaluate selected chemical protective clothing suitable for use by emergency response personnel confronted with methyl isocyanate (MIC). Twenty-two chemical protective clothing materials were tested against liquid methyl isocyanate. Chemical permeation breakthrough times for these clothing materials demonstrate that only one of these garments can be considered as a candidate material against liquid MIC. In a subsequent study, three chemical protective clothing materials were evaluated against approximately 800 ppm MIC vapor. Chemical permeation breakthrough times demonstrate that these materials can be considered candidate materials. A final study tested self-contained breathing apparatus (SCBA) diaphragms. Four SCBA diaphragms were tested and all experienced rapid breakthrough when exposed to liquid MIC. Next, three SCBA diaphragms were exposed to approximately 800 ppm MIC vapor. The data demonstrate that the SCBA should be worn inside a total encapsulating suit.