Mining Project: Evaluation of Methods to Inform Development of a Near Real-time Monitor for Measuring and Reducing RCS Exposures in Non-coal Mines

Principal Investigator
Start Date 10/1/2020

To develop novel and improved monitoring solutions for respirable crystalline silica that can be commercialized and subsequently provided to mine operators for the assessment of hazardous conditions in the field.

Topic Areas

Research Summary

Mine workers may be exposed to high levels of respirable crystalline silica (RCS) with the potential to cause debilitating diseases, yet to date there is no instrument available to measure exposure in real time. Such real-time measurements would enable health and safety professionals to better understand the nature of worker exposures and would enable mine workers to mitigate overexposures in real time.

In order to address this problem, research is needed to improve in-field methods to measure RCS that can be used to prevent overexposures. Gathering air samples of RCS for regulatory compliance in mining workplaces is typically done by collecting dust onto filters for lab-based analysis, but no field-portable method exists to quantitate the RCS on such samples. For metal/nonmetal (MNM) mines, the Mine Safety and Health Administration (MSHA) existing standard for RCS in MNM mines is 10 mg/m3/(percent respirable quartz + 2) (for samples where the RCS content is >1%) expressed as the concentration of respirable dust for a full shift or an 8-hour equivalent time-weighted average (TWA), which is quantified by x-ray diffraction (XRD) via a laboratory method.

In order to replicate such laboratory methods under field conditions, the proposed research will focus on investigating the potential application of a variety of spectrometric methods that have the potential to support development of a field-portable monitor for RCS. Justification for this work includes that it addresses the recommendations made by reviewers in the 2019 Mining Program review. The reviewers called for new research on the following topic areas, which will all be addressed to some degree by this proposed research: “more optimal dust suppression methods”; “ability to use less water for dust suppression”; and “linking research on engineering technologies with human factors/social science.”

In this project, the above issues will be addressed by way of three research aims, as follows:

  1. Gather field samples for lab evaluations, while assessing RCS exposure in MNM and stone, sand, and gravel (SSG) mines. To obtain the data required to address this aim, NIOSH researchers will visit stakeholder mine sites and take mine air samples periodically throughout the life of the project. The existing standard NIOSH methods will be used to obtain TWA silica concentrations for area samples.
  2. Evaluate candidate spectrometry techniques for their ability to quantify RCS. The design of a real-time instrument will entail critical choices for three interdependent requirements: the choices for spectrometry method, particle collection method, and type of collection media. For this reason, samples obtained in mines and generated in dust chambers for the purpose of evaluating various spectrometry methods will be gathered on various collection media, and several options will be explored to effectively measure infrared absorbance spectra.
  3. Develop a prototype real-time RCS monitor. Based on the results of the first two research aims, NIOSH researchers will choose a spectrometry method, a collection technique, and appropriate media. Then together with a suitable technology developer/partner, researchers will design a prototype by way of a cooperative research and development agreement. Specific spectroscopic requirements will be provided to the industry partner, who will be responsible for sourcing and assembling the required components.

Developing a commercially viable real-time instrument for measuring RCS will enable mine operators to assess and reduce exposures. The adoption of such technologies by industry has the potential to help identify mines and various tasks where RCS is a problem and to inform future mitigation strategies to control RCS at mine sites. This will help reduce workers’ exposure to RCS when working near the sources and may change the way regulations are made and enforced.

Page last reviewed: April 11, 2024
Page last updated: September 18, 2020