Department of mining engineeringMackay School of Earth Sciences and Engineering

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Contact: Professor Pierre Mousset-Jones (775) 784 6959 mousset@mines.unr.edu

Objectives

• Characterize chemical composition and particle size distributions of organic and inorganic contaminants from specific sources and in ambient air in underground gold mines;
• Apportion the contribution of specific sources (e.g., diesel equipment, mechanical particle generation, oil mist, cigarette smoke, etc.) to the total ambient airborne contaminant load in the mines; Estimate exposures of mine workers to these sources.

Background and Purpose

On October 29, 1998, the U.S. Department of Labor's Mine Safety and Health Administration (MSHA) proposed new rules that establish health standards for underground metal and non-metal (or non-coal) mines that use diesel equipment. The rule establishes a concentration limit that would be phased in over a five-year period. An interim limit of 400 *g/m3 of total carbon will go into effect following an 18-month period of MSHA education and technical assistance to mine operators. A final limit of 160 *g/m3 is become effective in five years. Surveys of some mines showed that the workers' exposures to diesel particulate matter (DPM) significantly exceed (on the order of few hundred percent) proposed health standards. However, the contributions of potential sources to worker exposure are not ce rtain. Reliable methods for measuring human exposure to diesel emissions and attributing source contributions are needed in order to develop effective approaches to attain the new standards.

Methods that are available for sampling and analysis of DPM in metal and nonmetal mines are:

• respirable combustible dust (RCD)
• size selective (SS) sampling
• elemental carbon (EC) analysis

Although each provides information concerning DPM, none measures DPM directly. Thus, a method is needed to evaluate EC analysis as a technique for estimating DPM exposure.

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