Based on a limited chemical mass balance analysis, two points can be made concerning the contribution of the various diesel mine sources to both fine and coarse fractions of the respirable aerosol concentrations in the metal and nonmetal mine environment: 1. Diesel exhaust aerosols are the dominant component of the submicrometer-mode aerosol measured in the diesel mines. More than 90 pct of the measured aerosols are contributed from diesel sources. 2. As much as 20 pct of the diesel exhaustaerosol contributes directly to the coarse part of respirable aerosol in the mine atmosphere. It is not clear that the size-selective technique used in the measurement of coal mine diesel aerosol can be extended to diesel-equipped metal and nonmetal mines. That technique depends on separating the collected aerosol sample into two size fractions at 0.8 Um. In metal and nonmetal mines the substantial contribution to the respirable coarse fraction made by diesel exhaust aerosol compromises the use of size-selective sampling, reducing the accuracy to less than 80 pct. As a result, alternate, carbon- specific, methods for determining diesel aerosol concentrations should be used in such mines if higher accuracy is desired. One such method is thermal-evolved gas analysis. This technique permits analysis of the volatile, carbonate, and elemental carbon fractions of an aerosol sample. It should permit an unambiguous analysis of elemental carbon (soot) in a mine aerosol sample.