Continuous Personal Dust Monitor

Until recently, underground coal miners and mine operators had little way of knowing—in real time—if miners were being exposed to hazardous levels of respirable coal dust during their shifts. NIOSH collaborated with an instrument manufacturer, government partners, labor representatives, and coal industry leaders to develop the continuous personal dust monitor (CPDM), a technology that offers miners, safety personnel, and operators real-time exposure information to help protect miners’ health.

Throughout their shifts, miners can read the digital screen on the CPDM to see their dust exposure levels for the previous 30 minutes, as well as their cumulative shift-long average. Workers and management can use this information to adjust dust controls or determine corrective actions—such as improved ventilation or repositioning miners to locations with less dust. The data recorded by the CPDM can also be uploaded to the Mine Safety and Health Administration sample collection database for determining compliance with allowable respirable dust limits.

Before the CPDM, mines had to collect samples on a filter and send them to a lab, where the samples were analyzed for hazardous dust. Shipping and lab time often took weeks—potentially leaving miners working in a dangerous situation. The CPDM reduces the reporting time to minutes.

Dust sampling in operating coal mines has been federally mandated since 1969 and is a critical part of checking whether the air that miners breathe underground is at or below allowable dust limits. MSHA mandated CPDM use for dust sampling in February 2016, and the industry is seeing the benefits of having this sort of information at workers’ fingertips. Early data reported to MSHA from users of this wearable device show miners are using the information the CPDM provides to move themselves to areas where dust levels are within safe limits and make ventilation adjustments to their workspaces to keep the dust moving away from them.

This development is critical, as breathing hazardous dust concentrations can cause coal workers’ pneumoconiosis, commonly known as black lung disease. Miners who suffer from black lung experience lifelong and irreversible breathing problems, often leading to premature death. An especially severe form of the disease, progressive massive fibrosis (PMF), is resurfacing, as was recently documented in the December 16, 2016, issue of CDC’s Morbidity and Mortality Weekly Report.

In addition to the medical and emotional burden that the disease places on workers and their families, there is also tremendous financial cost. The U.S. Department of Labor’s Black Lung Program has paid more than $46 billion in compensation to black lung sufferers since 1970, and more than $275 million in 2016 alone.

Black lung prevention and eradication is a priority for NIOSH. Decades of research have produced many effective dust control technologies for mines, including water sprays, protective air curtains, and air scrubbers. These solutions are detailed in the NIOSH publication, Best Practices for Dust Control in Coal Mining, and in many other resources available from the NIOSH Mining website.

The CPDM stands to be a powerful tool to prevent hazardous dust exposures, and hopefully keep future cases of black lung from developing, particularly for workers in positions prone to experiencing high dust levels.

The PDM3700, a certified and commercially available CPDM, is based on a proprietary technology known as the tapered element oscillating microbalance (TEOM) originally developed as a fixed-site environmental particulate mass monitor by Rupprecht and Patashnick Co., Inc., Albany, NY. NIOSH worked with R&P and its successor company, Thermo Fisher Scientific, as well as with labor unions, employers, and government partners to adapt that existing, larger technology into a smaller sampling device that could be safely worn underground.

 If you have used the CPDM we would love to hear from you in the comment section below.

Steven Mischler, PhD, is a senior research scientist in the Dust, Ventilation and Toxic Substances Branch of  the NIOSH Office of Mine Safety and Health Research.

Valerie Coughanour, MA, MFA, is a health communication specialist in the Health Communications, Surveillance, and Research Support Branch of the NIOSH Pittsburgh Mining Research Division.