Burden, Need, and Impact
There were approximately 202,000 workers in the Mining Sector in 2015—about 0.14% of the workforce, according to the Current Population Survey. MSHA reports 349,847 workers in mining in 2015. This sector accounted for 0.6% of the fatalities for U.S. workers. BLS data shows about 5,700 injuries and illnesses—about 0.2% of the total. MSHA data for the same period shows 26 fatalities and 7,192 reportable mining injuries and illnesses. These estimates vary due to differences in methodology and normal fluctuations in mining employment. Although injuries and illnesses are challenging to track and are frequently undercounted, these are the best estimates available at this time.
To help protect these workers, NIOSH strives to maximize its impact in occupational safety and health. The Mining Program identifies priorities to guide its investments in research, basing those priorities on the evidence of burden, need, and impact.
The NIOSH Mining Program establishes burden and need through surveillance data and statistics and stakeholder input. Surveillance data show how workers are being killed, injured, or impaired. Customers and stakeholders identify their needs and the value of our products and services, and we communicate with our stakeholders regularly to better understand those needs. We use risk analysis techniques to assess low-probability, high-impact events such as mine explosions. This allows us to effectively target research areas, set priorities, and assess impact. We then use an external peer-review process to evaluate our research proposals and ensure the scientific merit of our work.
Burden, need, and impact for the six Mining Program priority areas are detailed below.
Workplace solutions are adopted to reduce miner overexposure to hazardous airborne dust and diesel contaminants
Extracting and processing mined materials can result in overexposures to several hazardous airborne contaminants, including elongate mineral particles, coal dust, crystalline silica dust, and diesel exhaust. MSHA compliance data demonstrates overexposures to these airborne contaminants at rates as high as 24%. Overexposure to respirable coal dust can lead to coal workers’ pneumoconiosis (CWP), and exposure to respirable silica dust can lead to silicosis—both irreversible, disabling, and potentially fatal lung diseases. From 1970 through 2014, CWP caused or contributed to the deaths of 74,554 miners, with over $46 billion paid to compensate them and their families. Recent investigations show that progressive massive fibrosis (PMF), the most severe form of CWP, occurs at rates three times higher than any previously reported levels, and researchers believe that silica exposure may have contributed to these PMF cases. Exposure to diesel exhaust can affect both respiration and circulation. The International Agency for Research on Cancer (IARC) classifies both diesel engine exhaust and crystalline silica as carcinogenic to humans. Miners suffer from higher rates of asbestosis, lung cancer, and mesothelioma than other workers. In 2007, a mesothelioma cluster of 58 cases was found in 72,000 former taconite miners who worked in a large iron range in Minnesota, while the expected occupational mesothelioma rate is much lower at 1 per 200,000 workers.
Miners experience incidences of respiratory illness and disease that are much higher than the general population, and the standards for exposures to airborne hazards continue to be lowered based on new medical evidence. Most recently, the 2016 reduction of the respirable coal mine dust standard from 2.0 to 1.5 mg/m3 created a heightened need for effective controls. To address these needs, the NIOSH Mining Program continues to develop more effective methods to monitor and control hazardous airborne contaminants in mines. NIOSH is uniquely qualified to conduct this research due to its state-of-the-art laboratories, including full-scale longwall and continuous mining galleries where dust can be generated and measured without putting workers at risk, to develop and test dust controls. For diesel-powered equipment, the need is to reduce hazardous emissions from older engines being used in mines. NIOSH has extensive laboratories for developing and testing diesel controls, and these facilities are served by a dedicated team with two decades of experience and worldwide recognition for their diesel expertise.
NIOSH has developed improved control interventions to help industry reduce exposure to respirable coal dust, crystalline silica, diesel particulate matter, and elongate mineral particles. These interventions include the PDM 3700, a real-time respirable coal dust monitor commercialized by Thermo Fisher Scientific and required for MSHA compliance sampling; the Airtec, a real-time diesel particulate monitor commercialized by FLIR; and the Helmet-CAM and EVADE software monitoring technology that merges recorded video of worker activities and personal exposure data to identify sources of overexposure. An end-of shift silica monitoring technique is completing development to enable mines to perform silica analysis onsite and replace the traditional laboratory analysis method that required mines to wait weeks for the results. The NIOSH Mining program also has an extensive effort to develop control interventions for all of the above-mentioned hazardous airborne contaminants. For example, current research related to respirable coal mine dust exposures addresses over 60% of the overexposures experienced in coal mines. NIOSH is establishing a repository of characterized elongate mineral particles samples to support toxicology research, developing monitoring technologies to provide real-time data that can be used to prevent overexposures from occurring, and researching retrofitted diesel exhaust technology to help companies prepare for full integration of Tier IV EPA-rated low-emission engines into mines.
Workplace solutions are adopted that reduce miner overexposure to noise
Mining has a higher prevalence of hearing loss than any other major industry. A NIOSH analysis of over 1 million audiograms from 2000 to 2008 showed that 27% of miners had a material hearing impairment versus 18% for all industries. Mining has the highest prevalence of noise overexposure (76%) according to a NIOSH analysis of the 1999-2004 National Health and Nutrition Examination Survey (NHANES). Common equipment used in mines, such as continuous mining machines, rock drills, and roof bolting machines, generate sound levels over 100 decibels, which can lead to hazardous exposures within minutes. There are currently no requirements for mine equipment manufacturers to produce quieter equipment or state the noise levels of their equipment. Therefore, the burden is with the end user to either quiet the equipment through aftermarket noise controls or to limit operator exposure. To demonstrate, about 50% of jumbo drill machines used in the U.S. do not have cabs for the operators; therefore those operators are directly exposed to the noise generated by the machine processes. Although hearing loss does not typically result in loss of life, it greatly impacts the quality of the worker’s life, both on and off the job.
Our research specifically addresses a knowledge gap in noise overexposure that affects miners. Although MSHA collects noise exposure data via dosimetry for compliance determination, MSHA does not evaluate the actual noise levels produced by the machinery during operating conditions. We fill that gap by conducting laboratory and field research to determine overall sound levels and identify primary noise-generating components of machinery, and in turn develop suitable noise control solutions. The NIOSH Mining Program is ideally suited to develop these solutions, with a large hemi-anechoic chamber and a National Voluntary Laboratory Accreditation Program (NVLAP)-accredited reverberation chamber, large enough to test working mining equipment. We use the hemi-anechoic chamber in conjunction with an 84-microphone beamforming array to identify the physical location and the frequency content of dominant noise sources in mining equipment. This essential information helps us develop effective noise controls that directly address the dominant noise sources. We use the reverberation chamber to obtain accurate measurements of the sound power radiated by a mining machine before and after the developed noise controls are installed. This allows us to evaluate the performance, in terms of noise reduction, of the developed noise controls. These facilities, coupled with instrumentation, software, relationships with original equipment manufacturers, and expertise to develop engineering noise controls for mining equipment, uniquely position NIOSH as a leader in mining noise control development and testing.
NIOSH-developed noise controls have a high likelihood for continued impact by addressing hazardous noise at the source. Our partnerships with manufacturers allow us to act as close collaborators to develop and evaluate the feasibility of noise control properties, while allowing manufacturers to develop, market, and distribute the end products. NIOSH-developed noise controls that are currently available commercially include coated flight bar conveyor chains and dual sprocket conveyor chains, to reduce continuous miner conveyor noise levels, and drill bit isolators, to reduce noise exposure during underground coal roof bolt drilling. These noise controls, when installed, used, and maintained properly, can reduce the overall daily noise doses of the machine operator by 30-50%, as shown by the collective results from three NIOSH studies on coated flight bars for a CMM, a dual sprocket chain on a CMM, and noise controls for roof bolting machines. Joy Global also manufactured a longwall shearer drum with design modifications and engineering developed by NIOSH. Current NIOSH research is developing noise controls for jumbo drills used in underground stone and metal mines, and similar impact is projected. Future research will expand on the quiet-by-design approach to partner with manufacturers to design controls into machines during production.
Workplace solutions are adopted that enable mines to remediate risk factors for musculoskeletal disorders
Of all nonfatal occupational injuries and illnesses reported to MSHA between 2009 and 2013, nearly one-third (29%) were musculoskeletal disorders (MSDs). The median number of days lost, which is the sum of days lost from work and the number of days with restricted work activity, was 21 for all reported MSD cases. Musculoskeletal disorders have direct costs (medical plus compensation payouts) and indirect costs (lost wages, fringe benefit losses, training, hiring, and disruption costs, etc.). Older workers, and those with more mining experience, show more days lost from work as compared to their younger, or less experienced, counterparts, who show a higher frequency of injury. MSDs affect the quality of life of workers, limiting their physical capabilities, vitality, and even negatively impacting their mental health.
From an ergonomics standpoint, mining tasks that require forceful exertions, awkward postures, and repetition rates that pose a risk of musculoskeletal disorders are ubiquitous, and are present across mining commodities. Unusual postures and restricted spaces often exacerbate the exposure and risk. The NIOSH Mining Program is well-positioned to address these problems, and has been a significant contributor globally to mining ergonomics research over the past two decades. Our research team of biomechanists, ergonomists, and engineers uses an interdisciplinary focus to develop practical solutions to mining industry problems. In addition to work physiology, strength assessment, and motion analysis laboratories, NIOSH’s unique Human Performance Research Mine can be configured to mimic various underground mining scenarios, including operation of actual mining equipment, with state-of-the-art data acquisition capabilities that measure human performance parameters during simulated work. This mine allows researchers to conduct carefully controlled yet highly relevant studies that are not feasible in typical mining environments due to often harsh environmental conditions. Our researchers also maintain working relationships with mine operators that facilitate the access needed to conduct field assessments on site, and to determine the necessary characteristics for laboratory simulations. Working directly with mine operators helps us to fill knowledge gaps and ensure that our work is timely and targeted to reducing MSD risk factors.
NIOSH’s proven history of helping mines address ergonomics issues includes the publication Ergonomics and Risk Factor Awareness Training for Miners, which has been used extensively to educate miners about how their bodies age and steps they can take to protect their musculoskeletal health. More recently, ErgoMine, an Android application created by NIOSH, has delivered over 2,200 recommendations to miners in the first year after being published. ErgoMine provides customized recommendations for addressing observed ergonomics and safety issues detected by having the user answer a series of easy-to-understand questions or inputting weight and distance measurements. Future similar impact will be made in the area of slips, trips, and falls (STFs) through research to develop tools to identify, report, and remediate STF hazards in the workplace. These impacts will be achieved through significant field studies and interaction with miners, laboratory studies, and continued surveillance of injury and illness data.
Workplace solutions are adopted to eliminate fatalities and injuries caused by mobile and stationary mining equipment
According to MSHA data analyzed by NIOSH, from 2000 to 2015, a total of 885 fatalities occurred in mining. Metal/nonmetal mining operations had 431 fatal accidents and coal operations had 454. Of this total, 32% (281) were related to machinery or powered haulage, with striking and pinning of miners with a piece of equipment accounting for about 30% (84) of the machinery-related fatalities. Other causes of fatalities included entanglements with conveyor systems, especially for tasks associated with machine maintenance, repair, or cleanup. Fatal accidents involving conveyors accounted for 6% (53) of traumatic machine-related injuries. Maintenance accidents also made up a large portion of machine-related calamities, with about 30% (262) of total fatalities in mines due to entanglements and falls from height during maintenance.
The NIOSH Mining Program is uniquely positioned to perform research on machinery and powered haulage safety, with significant experience in designing engineering controls to prevent pinning and striking accidents. We have completed extensive research in proximity detection systems technology to improve the performance of systems being used in mines. The research findings have been incorporated in MSHA regulations and by industry on proximity detection systems for continuous mining machines (CMMs). Further, our human factors experts played a critical role in investigating risk perception and situational awareness considerations for the use of new technologies, and in developing the framework for health and safety management systems (HSMS). However, there still exists a need for additional research in this area because of lack of knowledge in applications of proximity detection systems to mobile equipment. NIOSH also has the facilities to conduct full-scale testing on mining machines and equipment, such as continuous mining machines (CMMs) and belt conveyors, using specialized measurement equipment in a controlled environment. Our industry partnerships leveraged over years of collaborations empower us to expedite development and implementation of machinery and powered haulage technologies based on our research, and to understand the end user’s perspective on accepting these technologies.
MSHA references NIOSH findings in numerous regulations, giving evidence to the NIOSH Mining Program’s impact on machine safety research for both mobile and static equipment. Specifically, MSHA cited NIOSH research in promulgating the use of proximity detection systems on CMMs and in the proposed rule for the use of these systems on other mobile equipment. The industry has adopted emerging technologies and engineering controls based on NIOSH research, which has also guided manufacturers in the design of commercially available systems. As one example, The Hazardous Area Signaling and Ranging Device (HASARD), invented by NIOSH, has been adapted by manufacturers of all MSHA-approved systems installed on CMMs and other types of mobile equipment. MSHA predicts that as many as 70 injuries could be prevented and 15 lives could be saved over the next ten years by utilizing proximity detection systems on mobile haulage equipment in underground coal mines. Based on MSHA’s economic analyses on regulatory impacts, this equates to approximately $512,000 for each injury prevented and $9.2 million for each life saved, for a total of over $173 million. The impacts attained by NIOSH research will empower the industry to reach and maintain a zero incident culture for injuries and fatalities due to mobile and stationary mining equipment. In addition, NIOSH will create recommendations to develop HSMS at mines to improve worker knowledge of hazards and risks at the organizational level. Ultimately, this approach will contribute to the elimination of fatalities and injuries related to mobile and static equipment and save the industry millions of dollars.
Workplace solutions are adopted to eliminate fatalities and injuries caused by rock falls between supports or loss of containment from damaged ribs
Ground falls remain a leading cause of fatalities in underground coal mines. From 2006 through 2015, a total of 52 ground fall fatalities and 2,721 non-fatal days lost (NFDL) injuries were reported by MSHA. Of these ground fall-related incidents, 11 fatalities and 668 NFDL injuries were caused by rib falls. The injuries and fatalities attributable to ground control failures are distributed among causes ranging from pillar failures to rock outbursts to insufficient standing support. Coal rib stability will continue to become a greater challenge as mining operations move into deeper reserves and encounter more adverse multiple seam stress conditions. Rib-related hazards are most likely to occur in the eastern coal basins of Appalachia and Illinois, which, according to a 2016 Annual Coal Report from the U.S. Energy Information Administration, represent 96% of all underground coal mined in the U.S.
Currently, U.S. coal mines primarily use a trial-and-error approach when designing rib support. To address fatalities and injuries resulting from rib falls, a mix of basic, intervention, and translational research is needed. This research requires an improved understanding of the mechanisms and the root causes that lead to rib falls; a practical protocol to quantify the structural integrity of coal ribs; an engineering-based coal rib design approach; and a definition of the minimum design requirements for rib control. Previous NIOSH Mining Program research has led to improved recommendations, best practices, and risk reduction methods. Nevertheless, lab testing, field instrumentations and observations, statistical analysis of empirical data, and numerical modeling are needed to expand our knowledge and datasets beyond current experience. Several resources unique to the NIOSH Mining Program provide us with the most comprehensive mining research abilities and facilities in the world, including a mine roof simulator; two research/experimental mines to test, calibrate, and experiment with instrumentation; and recognized experts in the various facets of ground control.
Recent NIOSH research provides a specialized model to simulate the stress-driven coal rib failure mechanisms observed in U.S. underground coal mines. NIOSH is currently using this model to identify critical parameters affecting coal rib stability and to develop an engineering-based design methodology. A design procedure will be provided that is similar to the NIOSH software products, ALPS, ARMPS, and AMSS, which have led to MSHA policy changes, ultimately resulting in a major reduction in injuries, fatalities, and difficult mining conditions. The developed rib design product will enable the mining industry and enforcement agencies, such as MSHA and state agencies, to assess rib integrity and to design appropriate rib controls. Other research projects are actively exploring alternative mining methods in challenging environments to improve mine stability, especially as metal mines reach deeper levels. New ground support and monitoring technology is also being studied to improve stability in high stress and weak rock conditions while lowering the cost of monitoring mining-induced seismicity. Universities, international research organizations, and future internal research efforts will rely on the outcomes of our ground control research to develop additional preventive solutions.
Workplace solutions are adopted to reduce the risk of mine disasters
According to MSHA data, since 2000, 64 U.S. mine workers have been killed and 10 injured as a result of fires or explosions in underground workings. Float coal dust, generated during coal mining, serves as fuel that can propagate an explosion flame, and the explosibility of float coal dust is controlled by applying “rock dust”—i.e., ground limestone dust—on all mine surfaces as an inerting agent. However, based on data from MSHA’s Mine Data Retrieval System, the industry received nearly 1,300 violations in 2016 for failure to maintain rock dust levels sufficient to limit float coal dust explosibility. Accumulations of methane gas are also a constant threat to the safety of underground mine workers. From 2000 to 2015, roughly 700 methane ignitions occurred during coal mining, generally during longwall mining. Ventilation airflow is the primary means of controlling methane levels, but such controls are challenged by more rapid mine development that liberates greater methane quantities, larger mining areas that create greater exposed coal surfaces, and larger gob areas under the influence of a single ventilation district. Finally, fires in a confined underground mine environment can produce catastrophic consequences. From 2000 to 2015, nearly 900 fires were reported that resulted in three fatalities. When the fire source cannot be readily diagnosed or remedied, the mine may be closed by MSHA for a minimum of six months to permit continued analysis of the fire’s behavior. Such an action can greatly stress or ruin the local economies dependent upon mine worker wages.
Federal regulations mandate that all underground coal mine surfaces be rock dusted; however, no standard protocol exists for evaluating the inerting performance of rock dust. A previous NIOSH study collected rock dust samples from various mining regions and discovered that nearly half of the samples did not meet minimum particle size requirements; of those that did meet the requirements, some did not inert coal dust. This study calls into question the effectiveness of rock dust products being used in underground coal mines, demonstrating the need for standard test protocols for use by manufacturers. To reduce disaster risk, effective ventilation on longwall mining units is also critical to controlling the large amounts of methane gas liberated during mining. Specifically, research is needed to quantify potential accumulations of methane at the longwall tailgate corner. Guidance on mine monitoring is also needed so that sensors can be properly deployed to maintain the effectiveness and utility of a monitoring system. Sensor deployment strategies must be developed and evaluated using performance-based metrics to ensure early detection of a combustion incident. The NIOSH Mining Program is uniquely qualified to conduct this disaster prevention work due to the high level of expertise of its researchers and the availability and access to the required laboratory apparatuses and in-mine facilities.
NIOSH Mining Program successes in reducing the risk of disaster are evidenced by the development of the coal dust explosibility meter, recommendations for a new rock dusting standard, software products such as MFIRE, and ongoing research on “smart ventilation.” Continued research in these areas will develop technologies that limit the generation and transport of float dust at the source and throughout mine workings. In addition, standard test protocols developed by NIOSH will be available to industry suppliers to assess rock dust effectiveness for inerting a propagating coal dust explosion. Mine operators will use NIOSH research findings to improve ventilation to minimize accumulations of methane gas at longwall tailgate corners, and NIOSH will develop new strategies that provide earlier detection of such accumulations along the longwall face area, thus reducing the number of face ignitions. Improved NIOSH-developed sensor deployment strategies will be performance-based, permitting early detection of fires and heating in the incipient stages of combustion and, perhaps, forestalling the long-term closure and sealing of the mine.
- Page last reviewed: 3/14/2018
- Page last updated: 3/14/2018
- Content source: National Institute for Occupational Safety and Health, Mining Program