Monitoring Diesel Particulate Matter and Calculating Diesel Particulate Densities Using Grimm Model 1.109 Real-Time Aerosol Monitors in Underground Mines

Abstract

Currently, there is no Mine Safety and Health Administra- tion (MSHA)-approved sampling method that provides real-time results for ambient concentrations of diesel particulates. This study investigated whether a commercially available aerosol spectrometer, the Grimm Portable Aerosol Spectrometer Model 1.109, could be used during underground mine operations to provide accurate real-time diesel particulate data relative to MSHA-approved cassette-based sampling methods. A subset was to estimate size-specific diesel particle densities to potentially improve the diesel particulate concentration estimates using the aerosol monitor. Concurrent sampling was conducted during underground metal mine operations using six duplicate diesel particulate cassettes, according to the MSHA-approved method, and two identical Grimm Model 1.109 instruments. Linear regression was used to develop adjustment factors relating the Grimm results to the average of the cassette results. Statistical models using the Grimm data produced predicted diesel particulate concentrations that highly correlated with the time-weighted average cassette results (R² = 0.86, 0.88). Size-specific diesel particulate densities were not constant over the range of particle diameters observed. The variance of the calculated diesel particulate densities by particle diameter size supports the current understanding that diesel emissions are a mixture of particulate aerosols and a complex host of gases and vapors not limited to elemental and organic carbon. Finally, diesel particulate concentrations measured by the Grimm Model 1.109 can be adjusted to provide sufficiently accurate real-time air monitoring data for an underground mining environment.

Keywords:

• cassette
• diesel particulate matter
• DPM
• Grimm Model 1.109 aerosol monitor
• underground metal mine

ACKNOWLEDGMENTS

The authors would like to thank Jared Lee and Greg Wolfley, students at the University of Utah Rocky Mountain Center for Occupational and Environmental Health; Steve McLaughlin, a safety supervisor at the Utah mine and Pete Day, an industrial hygienist at the Montana mine, for their assistance with coordinating and completing the DPM sampling periods; the University of Utah Division of Family and Preventive Medicine F. Marion Bishop Award for financial support; the State University of New York for the use of their Grimm Model 1.109; and the Centers for Disease Control and Prevention (NIOSH) Training Grant 2T42OH008414–03 for educational support.