The National Occupational Health Survey of Mining (NOHSM) was conducted at 491 mines during 1984 through 1989. There were 60 coal mines and 431 metal and nonmetal mines. The mines employed 59,734 miners, representing 66 mineral commodities. The survey at each mine included questionnaires, chemical inventories, and worksite visits. Questionnaire data included information on medical services, industrial hygiene practices, and general facility information. An inventory was made of chemical substances and trade name products on the mine property and their annual usage. Potential exposures at the mines were determined, based on observations and worker interviews. The projected numbers of potential exposures across the entire mining industry were estimated, based on the representative sample of mines in each mineral commodity. Because workers were often potentially exposed to more than one agent, the numbers of potential exposures may be greater than the total number of workers. It was estimated that in the entire mining industry, there were over 365,000 potential exposures to physical agents; over 710,000 potential exposures to musculoskeletal overload conditions; and over 188,000 potential exposures to welding, brazing, and soldering agents. Approximately 214,000 miners were found to be potentially exposed to dust that contained greater than 5% quartz (14808607).