Mining Contract: Respirable Coal Mine Dust (RCMD) Research: Characterization, Deposition, Monitoring, and Mitigation of RCMD and Capacity Building for Mine Health and Safety

Contract # 75D30119C06390
Start Date 9/15/2019
Research Concept

In addition to conducting a comprehensive study of the characterization, respiratory deposition, monitoring, and mitigation of respirable coal mine dust (RCMD). The investigators will use an innovative Mobile Aerosol Lung Deposition Apparatus (MALDA), to thoroughly and systematically estimate the RCMD respiratory deposition and the effect of the RCDM characteristics on the respiratory deposition. The effort will also advance the understanding of dust control through the study of the surface chemistry of the RCMD and its interaction with water droplets and potential methods to enhance the capturing efficiency, an evaluation of the efficacy of ultrasonic atomizing nozzle system to mitigate submicron dust particles, and investigation of the deposition of agglomerated particles in the human lung. The investigators will use the work to train, educate, and graduate eight mining engineering graduate students and generate expertise in the area of mine health and safety, dust control, and mine ventilation, further building capacity in the field for future research. The expertise of the team members in areas of mine ventilation, fluid mechanics, surface chemistry, and industrial hygiene will be utilized in advancing science and technology related to dust control and monitoring, thereby, reducing RCMD exposure in underground coal mines.

Contract Status & Impact

This contract is ongoing. For more information on this contract, send a request to mining@cdc.gov.

If inhaled, the respirable dust can penetrate through the upper tracheobronchial (TB) airways and enter into the lower TB airways as well as the alveolar region. Respirable coal mine dust (RCDM) in underground mines consists of a mixture of very small particles of coal, silica, silicate minerals, and other minerals as well as organic materials found in the mine environment. The inhalation of RCDM, depending on its concentration, exposure duration, and characteristics, can cause incurable lung diseases, including coal workers’ pneumoconiosis (CWP, also known as black lung disease), silicosis, and progress massive fibrosis (PMF).

In the U.S., after the implementation of the interim coal mine dust standard of 3.0 mg/m³ in 1970, and the final standard of 2.0 mg/m³ in 1972, the prevalence of CWP and concentrations of coal mine dust declined. However, there has been a resurgence in disease incidence since the mid-1990s. A study conducted by NIOSH in 2005 reported rapidly progressive disease among coal miners. The study revealed that among miners with pneumoconiosis, 35% were diagnosed with rapidly progressive disease, including 15% with the most severe and often lethal form, PMF. Recent medical surveys further reveal that relatively young miners who have spent their entire employment working under modern dust control regulations are being similarly affected. Such rapidly progressive pneumoconiosis has been observed mainly in the Appalachian coal fields of Kentucky, Virginia, and West Virginia.

The geographical clustering of pneumoconiosis has been speculated to be mainly due to mining thin-coal seams in these areas, necessitating cutting significant amounts of roof and floor rock to access the seam. The out-of-seam materials are mostly comprised of silica (i.e., quartz) and silicate minerals (cyclosilicates, phyllosilicates, tectosilicates, etc.), which have been associated with severe lung diseases. Other potential factors such as coal rank, mine size, mining method, coal- and rock-strata geological conditions, duration and level of exposure, dust characteristics (i.e., size, shape, mineralogy, elemental content), and dust mitigation techniques have been also suggested as contributing factors to the recent trend.

The recent resurgence of lung disease in miners has raised concern in the scientific and regulatory community. To address this concern, the Mine Safety and Health Administration (MSHA) issued the 2014 dust rule changing the RCMD allowable limits, measurement technology, and sampling protocol for RCMD exposure. However, a number of researchers have questioned whether the reduced limit would target the root problem. A 2018 report by the National Academies of Sciences, Engineering, and Medicine highlighted the need for research efforts with respect to “respirable coal dust characterization and deposition, sampling protocol, and monitoring strategies for controlling miner’s exposure to RCMD.”

This research, therefore, intends to fill the knowledge and technology gaps in characterization, respiratory deposition, monitoring, and mitigation of RCMD. 

The research team will:

  • Investigate the characteristics of respirable coal mine dust in west and east coal regions, and the relationship between the characterization and respiratory deposition of RCMD on the lungs.
  • Analyze the surface chemistry characteristics of respirable coal dust in order to understand the interaction of RCMD particles with water droplets, particularly as the particles interact with water from different water spray nozzles intended to work within a mine ventilation strategy.
  • Evaluate the efficacy of ultrasonic atomizing nozzle system to mitigate submicron dust particles, and to investigate the deposition of agglomerated particles in the human lung.
  • Investigate the effectiveness of mass-concentration-based and number-concentration-based RCMD sampling techniques for estimation of the true dose of RCMD deposition on the lungs as compared to MALDA estimates.
  • Develop a respirable coal mine dust exposure predictive model in order to estimate the level of exposure at various locations of an underground coal mine.
  • Train and educate 3 Ph.D. and 5 M.S. graduate students in Mining Engineering and develop new expertise in mine health and safety with the emphasis on mine dust control.

Page last reviewed: 2/5/2020 Page last updated: 2/5/2020