Health hazards of diesel and electric vehicles in an underground coal mine

Results of an engineering assessment of potential health hazards, both air quality and noise, are reported for diesel and electric face-haulage equipment operating in the same underground coal mine. The effects of four parameters were investigated: (1) type of car, (2) number of cars, (3) sample location, and (4) airflow quantity. Instruments were chosen for integrated gas sampling (long-term detector tubes) that were reliable, reasonably priced, and suitable for routine use in the underground environment. Particulates and noise were measured instantaneously with direct-reading instruments. In the section using diesel ram cars, none of the shift-long measurements of carbon monoxide, carbon dioxide, particulates, or noise violated threshold limit values (TLVs). About 2% of the measurements of nitrogen dioxide and nitric oxide exceeded TLVs. Particulates were excessive only in the section using electric shuttle cars. When three rather than two diesel cars were used, emissions increased approximately proportionately. Of three locations sampled, in all instances, the discharge point consistently registered higher than the face and on board the cars, but there was only a poor correlation between diesel-emission concentrations and airflow quantity. Evidence was lacking of a significant health hazard due to diesels at the mine under study.