A survey of elemental carbon (7440440) levels at a potash mine and mill was conducted. Area and personal air samples were collected over a 3 day period in the repair shop, underground in the overhaul shop, on a continuous haulage section, and on a ramcar section. Area air samples were also collected in an office and outdoors near the mine exhaust shaft on the surface. Samples were analyzed for diesel particulate matter (DPM) and elemental carbon, used as a surrogate for diesel exhausts. Elemental carbon levels on the surface measured in the area air samples ranged from 0 to 27 micrograms per cubic meter (microg/m3). Area air elemental carbon levels in the samples taken underground varied from 17 to 606microg/m3. The highest average exposure over the 3 day period, 453microg/m3, was measured in the ramcar section. The lowest average exposure was measured in the overhaul shops, 60microg/m3. DPM concentrations ranged from 116 to 279microg/m3 at the surface locations and from 104 to 1,035microg/m3 at the underground locations. The highest average DMP concentration measured underground, 798microg/m3, was in the ramcar section. The elemental carbon and DPM concentrations were highly correlated, correlation coefficient 0.98; however, the elemental carbon/DPM ratios were not constant but increased with increasing elemental carbon and DPM concentrations. In the underground personal air samples, ramcar drivers had the highest personal exposures, 345microg/m3. Underground mechanics and others working in shop areas had the lowest exposures, 53microg/m3. On the surface, mechanics had the highest personal exposures, average 31microg/m3. Comparing the mean personal elemental carbon exposures indicated that the workers could be divided into three groups: high, medium, and low exposure. Ramcar drivers were in the high exposure group, other underground mining workers were in the medium exposure group, and underground maintenance and all surface workers were in the low exposure group. The authors conclude that exposure to elemental carbon varies widely among different occupational groups.