Quantitative measurement of diesel particulate matter in an underground coal mine using laser Raman spectroscopy

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The use of diesel-powered equipment in coal mines is increasing. Diesel particulate matter (DPM) found in the respirable dust in underground coal mines has been of concern as an additional health hazard because DPM has been found to be a mutagen and/or carcinogen. Although the regulated exposure limit has not been established, there is a need to control DPM. In order to control DPM effectively, it must be measured quantitatively. The Laser Raman Quantitative Analysis (LRQA) technique was developed to measure the fractions of diesel particulate and coal dust on a filter similar to the filter currently used to measure the mine ambient air concentration of respirable coal dust. This article discusses use of the LRQA method to determine the fractions of diesel and coal aerosol in a fourth U.S. underground coal mine. The LRQA method has several advantages, that is, the measurement is independent of the particle size and there is no sample preparation that may alter the sample. This article discusses refinements made in the sample collection procedure and in the method used to calculate the Raman spectral intensity ratio using a polynomial baseline. The LRQA measurement results were compared with data obtained by the size-selective method, using personal dichotomous samplers. The samples analyzed by the two techniques were collected simultaneously and at the same locations in the mine. Use of the polynomial baseline in the Raman analysis provides DPM concentration data that are more reproducible than those obtained earlier using a linear baseline. The polynomial baseline Raman data also compare more closely to the size-selective personal dichotomous sampler results than do the Raman data obtained using a linear baseline. © 1996, Taylor & Francis Group, LLC. All rights reserved.

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Applied Occupational and Environmental Hygiene