Evaluation of the GMD systems, Inc., thermally-desorbable diffusional dosimeter for monitoring methyl chloride

The GMD Systems, Inc., thermally-desorbable diffusional dosimeter using Anasorb GM solid sorbent was evaluated for monitoring methyl chloride (CH3Cl) in the workplace. The effects of CH3Cl concentration; dosimeter exposure time; relative humidity, temperature, and face velocity during exposure; excursion exposure behavior; and storage temperature and duration after collection were investigated. Only extremely low face velocities (0.020 m/sec) and storage periods of over 8 days at room temperature or of around 30 days at reduced (refrigerator or freezer) temperatures caused sample degradation. Side-by-side measurements of CH3Cl using the diffusional monitor and a validated charcoal tube method under field conditions yielded statistically indistinguishable results. This diffusional monitor used in combination with Anasorb GM solid sorbent is a satisfactory means of determining CH3Cl exposures in the workplace.