Evaluation of the Approach to Respirable Quartz Exposure Control in U.S. Coal Mines

Abstract

Occupational exposure to high levels of respirable quartz can result in respiratory and other diseases in humans. The Mine Safety and Health Adminstration (MSHA) regulates exposure to respirable quartz in coal mines indirectly through reductions in the respirable coal mine dust exposure limit based on the content of quartz in the airborne respirable dust. This reduction is implemented when the quartz content of airborne respirable dust exceeds 5% by weight. The intent of this dust standard reduction is to restrict miners' exposure to respirable quartz to a time-weighted average concentration of 100 μg/m(3). The effectiveness of this indirect approach to control quartz exposure was evaluated by analyzing respirable dust samples collected by MSHA inspectors from 1995 through 2008. The performance of the current regulatory approach was found to be lacking due to the use of a variable property-quartz content in airborne dust-to establish a standard for subsequent exposures. In one situation, 11.7% (4370/37,346) of samples that were below the applicable respirable coal mine dust exposure limit exceeded 100 μg/m(3) quartz. In a second situation, 4.4% (895/20,560) of samples with 5% or less quartz content in the airborne respirable dust exceeded 100 μg/m(3) quartz. In these two situations, the samples exceeding 100 μg/m(3) quartz were not subject to any potential compliance action. Therefore, the current respirable quartz exposure control approach does not reliably maintain miner exposure below 100 μg/m(3) quartz. A separate and specific respirable quartz exposure standard may improve control of coal miners' occupational exposure to respirable quartz.

A Computer-Controlled SEM-EDX Routine for Characterizing Respirable Coal Mine Dust

“…While these alarming trends have not been fully explained, a number of causal factors have been suggested (e.g., see [14][15][16][17][18][19][20][21][22][23]), including exposure conditions and specific dust characteristics. , and includes all reported categories of CWP (i.e., severity categories 1, 2, and 3, and progressive massive fibrosis (PMF)).…”

“…The roof rock (e.g., sandstone) in many of these mines includes significant silica content, and so higher concentrations of crystalline silica (quartz) may be expected in dust [19,23]. Many mines in parts of central Appalachia are also relatively small and accordingly have small labor forces.…”

An Event Reporting and Early-Warning Safety System Based on the Internet of Things for Underground Coal Mines: A Case Study

“…Underground coal mine operation has always proved to be a very dangerous and hazardous environment [1] due to the presence of coal dust, methane, and other toxic gases [2,3]. It has been reported that approximately 33.8% of deaths that happen in the mining sector are a consequence of coal dust or methane gas explosions.…”

“…(2) We propose the seamless integration of key technologies of information systems based on IoT and cloud services for underground mine informatics, in which a cloud server communicates with mobile devices. (3) We originally proposed a single "Mine Warning Index (MWI)" for an easy and quick assessment of mine safety.…”

Characterizing Particle Size Distributions of Crystalline Silica in Gold Mine Dust

“…In the U.S., silica can be found in the respirable dust of coal mines, metal mines, and sand and gravel operations (Joy, 2011; Watts et al , 2012; Cauda et al , 2013). In coal mines, the primary source of mineral dust is the top strata above the coal seam (Schatzel, 2009); in non-coal mines, silica is a component of the dust present throughout numerous mining processes (Cares et al , 1973; Cauda et al , 2013); and in the industrial sand mining sector, crystalline silica in the form of sand is the main product of the industry.…”