Respirable Dust Hazards

coaldustDust can be generated in mining operations, sometimes in dangerous amounts that if inhaled by workers can cause disabling or even potentially fatal diseases. In coal mining operations, the extraction, crushing, and transport of the coal can produce airborne respirable coal dust. In metal, nonmetal, stone and sand and gravel mining operations, and in some coal mines, significant levels of respirable silica dust can be generated.

Inhalation of respirable coal dust by miners can cause pneumoconiosis (CWP), which is a disabling and potentially fatal lung disease. Inhalation of respirable silica dust can lead to silicosis, another disabling and potentially fatal lung disease. After a 30-year downward trend in CWP, it has become prevalent again. During the 1990s, twenty-three percent of those who died of silicosis were miners.

One of the top goals of the Office of Mine Safety and Health Research (OMSHR), a division of the National Institute for Occupational Safety and Health (NIOSH), is to reduce the incidence of respiratory diseases among miners. OMSHR hopes to achieve this through research to develop improved dust control technologies which would minimize the amount of airborne respirable dust. The dust control research has four components: intramural engineering control, funding of extramural research projects, technology transfer, and improved dust monitoring capabilities.

The intramural research is being done in both the coal and metal/nonmetal mining industries. Compliance sample data is analyzed and the occupations within each industry that are at highest risk for exposure to elevated dust levels are identified. Once the occupations have been identified, the control technologies can be developed and evaluated in the controlled conditions of laboratories. Once technologies are found to be successful in the laboratory they are evaluated at operating mine sites.

OMSHR also provides funding for extramural research projects that focus on the reduction of dust levels in mining operations. These include research being conducted on ventilation, and on the potential of utilizing particle charging and wetting characteristics of respirable dust particles to improve capturing airborne dust.

Technology transfer is the educational arm of OMSHR and involves creation and distribution of publications such as “Best Practices for Dust Control in Coal Mining” and “Best Practices for Dust Control in Metal/Nonmetal Mining.” OMSHR has also partnered with the Industrial Minerals Association-North America (IMA-NA) to produce a dust control handbook which covers control technologies for mineral processing operations. Publications such as these can aid mine operators in identifying and implementing the most successful and effective control technologies for their respective mines. Another venue for OMSHR’s technology transfer is a series of “best practices” workshops conducted in mining regions throughout the country. These presentations are also available on videos that can be downloaded from the NIOSH Mining website.

The fourth are of research involves real-time monitoring of respirable dust exposures to identify potential overexposures and then implement interventions to control these overexposures. A personal dust monitor (PDM) was developed by NIOSH through intramural and extramural research that has been proven to be an accurate dust sampler. In the respirable dust regulations that MSHA has proposed, and which are in the final stages of the rulemaking process, the use of the PDM is specified for compliance dust sampling.

A list of all the publications available from OMSHR on dust control can be found on their website at http://www.cdc.gov/niosh/mining/topics/RespirableDust.html.