Abstract The concern with the possible negative health effects of diesel exhaust in the mining environment has increased with the economic incentives for wider use of diesel-powered equipment in mining operations. The evidence derived primarily from inhalation studies has shown that diesel soot is a carcinogen for laboratory animals. Such results have led the National Institute for Occupational Safety and Health to recognize that diesel exhaust is a potential health hazard and that although the risk for workers exposed to diesel exhaust has not yet been quantified, exposure to such exhausts should be minimized. We have proposed to attempt to characterize and to allocate the source of various diesel soots. The differences in soot structure, because of the complexity of the soot lattice, may not be easily quantifiable with the human eye; therefore, high level computer software has been used to manipulate high resolution transmission electron microscopy (TEM) images of in-mine diesel soots in order to extrac...