Surveys of systems for the control of health hazards arising from the use and processing of mercury (7439976) were conducted during 28 site visits to 24 facilities. These facilities included manufacturers of batteries, thermometers, fluorescent lamps and electrical switches, chemical processing and production operations, and dental clinics. The control of worker exposure to mercury at all the facilities, except the dental clinics, was the result of an integrated control approach that included engineering controls, personal protection, and monitoring programs. Engineering controls consisted of local exhaust ventilation, temperature control, and a mercury pill. Airborne mercury concentrations at most sites were below the OSHA standard of 100 micrograms per cubic meter (microg/m3). In some cases, concentrations were below the NIOSH recommended standard of 50microg/m3. Mercury concentrations above 100microg/m3 were observed in the button cell cathode protection and anode gel preparation processes during battery manufacture, furnace and concentration areas in cinnabar processing, and in the spray drying and reactor and drumming areas during phenylmercuric-acetate manufacture. In these operations, full time use of respirators is recommended until appropriate control measures are instituted.