A field survey was conducted at the chloromethylmethylether (107302) (CMME) facilities of the Dow Chemical Company (SIC-2869) in Midland, Michigan, on September 8, 1972. The production process, exposure potential, and protective measures practiced by the company and its workers were considered. The company employed approximately 12,000 to 16,000 persons. Approximately 4,000 blue collar workers were involved with chemical production. The production system was self contained within the processing equipment, ventilation was provided at potential leak sites, and respiratory protection was provided for emergency access. The number of personnel was kept minimal in production areas. Laundered clothing and paid shower time was provided by the company when necessary, and medical services were provided by 4 or 5 industrial hygienists, 10 technicians, 10 safety advisers, 4 physicians, and 50 full or part-time nurses. The company collected personal and area air samples for CMME and an impurity, bis(chloromethyl)ether (542881) (bis-CME), from 1949 to 1972. The current continuous monitoring system utilized an infrared analyzer. The highest time weighted average (TWA) exposures to CMME and bis-CME during August, 1972 were 0.838 parts per million (ppm) and 0.610 parts per billion (ppb), respectively. TWA exposures to CMME for seven operators and to bis-CME for 4 operators ranged from 0.10 to 0.43ppm and 0.082 to 0.201ppb, respectively.