Coal Age

JAN 2016

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While sampling respirable dust in mines, miners who spend their shift working in dusty conditions typically have the same questions at the end of a shift: "What is the level of dust in my area?" and "when will I know the results of the samples from my section?" These questions are logical, per- sonal and reflect a health-related interest in the air quality of the work environment where miners spend a good amount of their time. Most miners are fully aware that expo- sure to high concentrations of respirable dust and crystalline silica (hereafter simply silica) can affect their health and future life, and many miners with longer tenure have co-workers who suffer from lung diseases caused by dust present in mines. In coal mines, these lung diseases have very well- known names — coal workers' pneumoco- niosis (CWP), or black lung, and silicosis. It is very disheartening for researchers and mine operators not to have immediate answers to these questions. The traditional dust monitoring approach entails the col- lection of dust samples on a filter medium, and the analysis of the dust collected and silica content are conducted in a certified laboratory with sophisticated instrumenta- tion. Generally, days or weeks pass before results can be summarized in a report to be shared with the mine, and eventually with the workers who asked those important questions. Many health and safety managers at coal mines collect respirable dust samples in the mine to check the silica dust levels, even though the new coal dust rule does not require them to do so. This reflects a grow- ing health and safety culture that goes beyond just being in compliance with the Mine Safety and Health Administration (MSHA) dust rule — coal mines want to pro- tect their workers by keeping silica dust lev- els low. Low levels can be achieved efficiently and cost-effectively with estab- lished control technologies, especially if mines have timely access to data on silica levels. Today's mines need a new solution to check silica levels and to have data by the end of the shift — one that is accurate, portable, fast and user-friendly — so that any engineering or operational adjustment can be implemented within the next few shifts. Recent Monitoring Improvements The introduction of the personal dust mon- itor (PDM) in coal mines has changed the traditional dust level measurement paradigm for the first time. Now every work- er wearing a PDM will have an indication of his or her exposure to respirable dust during the shift, and accurate information on the shift average exposure at the end of the workday. The data stored in the PDM can also be used to identify tasks with high dust concentration levels and allow operators to act before the following shift. While the PDM is a revolutionary improvement over the traditional dust monitoring approach, it is not selective in monitoring the components inside the dust — specifically silica. Exposure to silica in coal mines is the major cause for the devel- opment of silicosis and lung cancer, and a significant contributor to black lung. Silica is an inherent part of the dust present in a coal mine, but the silica content in the dust is highly variable both in space and over time. Because of this variability and the seri- ous health effects related to the exposure, MSHA has included in the new dust rule a stand-alone exposure limit for silica con- centration, in addition to the adjustment of the allowed dust exposure limit. The Office of Mine Safety and Health Research (OMSHR), part of the National Institute for Occupational Safety and Health (NIOSH), has recently started an initiative to provide mines and mine workers with an innovative solution for measuring silica lev- els in airborne respirable mine dust and obtaining results at the end of the shift. When optimized, this new approach will use a small portable instrument into which a dust sample cassette will be inserted, and in a few minutes the silica present on the fil- ter will be quantified. With just a few simple steps — including measuring flowrate and r e s p i r a b l e d u st January 2016 www.coalage.com 31 Figure 1 — Silica content in respirable dust samples collected in an underground coal mine in eight consecu- tive days. Minimum (green) and maximum (red) silica content is displayed for each day. B Y E M A N U E L E C A U D A , L A U R E N C H U B B A N D A R T M I L L E R Silica Adds to Respirable Dust Concerns What if you could know the silica dust levels in a coal mine after every shift?

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