PURPOSE:  Protect miners working in underground mines from diesel-powered equipment emissions through improvements in diesel particulate emission measurement techniques.

RESEARCH SUMMARY:  Long-term exposure to elevated concentrations of diesel exhaust has become a concern because diesel particulate matter (DPM) is considered to be a carcinogen by several organizations. Approximately 30,000 underground miners are exposed to excessively high DPM concentrations (greater than 500 g/m3). Since DPM consists of over 80% total carbon (TC), the Mine Safety and Health Administration (MSHA) initially chose TC as the surrogate for DPM. TC is the sum of organic carbon (OC) and elemental carbon (EC) fractions. The problem with TC is the number of other TC sources, besides DPM, in the mining environment. Research has shown that these TC interferences, such as mineral dust and vapor-phase OC, can be eliminated or corrected, but airborne contaminants like, cigarette smoke and oil mist, cannot.

In light of the problem with TC interferences, EC, with NIOSH influence, has become the surrogate for DPM. The problem with EC as a surrogate is that the relationship between EC and total DPM can change, depending on engine duty cycle and other factors.

Because of programmatic effort, several notable outcomes have been accomplished. MSHA has changed the DPM concentration surrogate from TC to EC. This change allows MSHA personnel to take interference-free samples to more accurately evaluate miner exposures. DPM cassettes, designed through Bureau of Mines/NIOSH research and manufactured by SKC, Inc., have become the standard DPM sampling technique. MSHA, industry, and labor have agreed on an interim DPM exposure limit. Finally, the underground mining industry, labor, and government have created a partnership to address issues relative to DPM exposure.

Several other diesel emission monitoring problems related to miner health exist that are being studied under this project. The relationship between EC and total DPM must be investigated, especially as new emission control technologies are implemented. Novel methods for determining and characterizing diesel emissions need to be developed. Finally, the industry is in need of a device that will enable personnel to determine real-time DPM concentrations in the mining environment