The use of diesel equipment in underground coal mines is controversial because "whole diesel exhaust" is regarded as "a potential occupational carcinogen" by the National Institute for Occupational Safety and Health. Threshold limit values (tlvs) are recommended for the gaseous pollutants CO, co2, no, NO2, so2, and some hydrocarbons emitted in diesel exhaust. There is, however, no tlv recommended for diesel exhaust aerosols, nor is there a standard method for sampling these aerosols. The University of Minnesota and the Bureau of Mines have collaborated to develop a personal diesel exhaust aerosol sampler which utilizes size-selective, inertial impaction and gravimetric analysis. During the field test of this sampler, numerous air quality measurements were conducted in underground coal mines using diesel equipment. The objective of this report is to present these data and to assess the impact of diesel face haulage equipment on mine air quality.