Mining Project: Emerging Respirable Dust Sensing and Control for M/NM Mining
To demonstrate the suitability and efficiency of monitoring and control solutions which will help to lower the respirable dust exposure of M/NM miners.
Workers in the metal/nonmetal (M/NM) sector may be exposed to respirable crystalline silica (RCS) as a result of normal mining and processing operations. RCS exposure is a serious health hazard and causes a variety of debilitating lung diseases for which the only cure is prevention. MSHA compliance respirable dust sampling in M/NM shows that between 2010 and 2020, 10% of the respirable quartz samples collected were greater than the 100 μg permissible exposure limit (PEL), with 31% greater than 50 μg.
In addition to silica, exposure to welding fume is a health hazard that poses many serious risks, including welding fume fever, lung and nasal cancers, manganese poisoning, and acute respiratory disease. While miners are sampled infrequently for welding fume, chemical exposure health data from the Occupational Safety and Health Administration (OSHA) found that between 2000 and 2015, 25% of all manganese samples collected were greater than the PEL.
These data on RCS and welding fume sampling are in themselves concerning, but become even more so because the current quantity of compliance sampling and internal mining company health sampling programs are too infrequent to impact worker health in near or real-time. While a variety of engineering and administrative controls exist to limit worker’s exposure to respirable crystalline silica, the adoption of these technologies could be increased with “smart” systems—i.e., lower-cost, real-time dust sensing networks and associated control technologies. High-accuracy continuous plant and equipment dust measurements would provide the data necessary to facilitate the next era of exposure assessment, where industrial hygienists make use of big data to lower high respirable dust level areas at mines. Further, the testing and dissemination of effective welding fume controls in real-world mining settings would increase their visibility, leading to more frequent adoption of these controls and the lowering of toxic metal fume exposure for mine workers. Finally, performance assessment of coated sands in field testing would quantify the effectiveness of these treatments to ensure that safety professionals accurately know their capability and limitations.
This project research will address these needs by way of three research aims and related tasks, as summarized below.
- Characterize the performance of low-cost dust sensors and evaluate their use in operational environments. To accomplish this, testing will be conducted comparing the output of low-cost dust sensors and traditional sampling methods exposed to dust types and concentrations found in the M/NM industry. Assuming that controlled aerosol chamber testing shows promise, the research scope will then be incrementally widened to determine the applicability of such sensors to more representative real-world conditions.
- Specify, construct, and demonstrate smart filtration and pressurization systems for mobile equipment. In performing this research, NIOSH will further the translation of research to practice, guiding the manufacture of a prototype system capable of implementing already-published principles of filtration best practice. Achieving this aim will encourage major equipment manufacturers to incorporate state-of-the-art filtration and pressurization on their cabs to ensure that acceptable air quality is continuously maintained.
- Quantify the effectiveness of emerging dust control technologies that have the potential to lower worker’s exposure to RCS and welding fume in the M/NM industry. The goal of this aim is to provide the mining industry with case-study assessments of the efficacy of specific control technologies, particularly those that have been developed to address reduced exposure PELs.
Practical, affordable, continuous smart dust sensing and control systems would greatly improve M/NM mining operations’ ability to identify trends in high dust exposures and provide the opportunity to immediately make process adjustments to lower these exposures. This awareness of continuous dust levels, combined with the mines’ efforts to reduce them, is ultimately what will improve miner health. By dissemination of the results of this research by NIOSH, an opportunity exists to implement proven principles into an integrated smart cab filtration system. More timely and informed decision making from smart cabs will reduce exposures and improve miner health.
New dust and fume engineering controls and interventions are ever-emerging, indicating great promise in lowering workers’ exposures, but these controls and interventions are not always supported by objective scientific evaluations. This project research will provide such evidence, including field evaluation of coatings to reduce respirable dust emissions on industrial sands, as exemplified by prior NIOSH engineering control assessments.