Continuous Personal Dust Monitor

Posted on by Steven Mischler, PhD, and Valerie Coughanour, MA, MFA
A continuous personal dust monitor at use in a mine.

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.



Posted on by Steven Mischler, PhD, and Valerie Coughanour, MA, MFA Tags

5 comments on “Continuous Personal Dust Monitor”

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    Excelente equipo que permite obtener información precisa y en tiempo real, felicitaciones.
    Consulta este equipo puede ser utilizado para monitoreo de polvo con sílice ya sea en minería subterránea o de cielo abierto.

    English Translation:
    This is excellent equipment that allows the user to obtain precise information in real time, congratulations.
    This equipment can also be used for monitoring silica dust in underground or open mines.

    NIOSH is currently evaluating methods to use the PDM for EOS measurements for silica and is looking for partners in this research. The following link directs to the website for the project.

    Spanish translation by Sue Afanuh
    Actualmente, NIOSH está evaluando métodos de uso del monitor personal de polvo para medir los niveles de fin de turno para sílice y está buscando socios para esta investigación. El enlace siguiente lleva directamente al sitio web del proyecto.

    I am a safety tech for a large underground coal mine in the USA. I personally program, clean and maintain, and calibrate nearly 70 model 3700 PDMs. Believe me when I say they are very aggravating at times.
    Here are a few examples of problems I have encountered with 3700’s:

    There are instances when the data freezes in both the CSV file and on the screen. When the data freezes it causes an unfortunate spike resulting in a voided sample.

    Regardless of how well you think the charger is connected do not attempt to program individual PDMs for consecutive shifts. Voltage levels need to be monitored after the charging light turns green due to potentially poor charging connections.

    Yes the sampling hose is made of fairly tough rubber but it will kink in a split second causing a loss in flow. This can cause multiple status conditions such as high filter loads and mass offsets resulting in voided samples. We went to the local hardware store and obtained stainless steel springs that we slid over the tubing clip and fed the tubing back through both to the cyclone. This has not eradicated all kinked hoses though it does help.

    Since the respirable dust standard changed to 1.5mg/m3 and several aspects of what defines a voidable mass offset where altered, PDM3700’s don’t always show a mass offset status condition when they should. I assume the instruments are programmed for the old rule and there are no current updates for that issue. The only true way to determine what time the wearer encountered the mass offset is to review all 5-600 lines of the CSV file and find a distinct change. Initially we could determine if the mass offset did or did not occur and if it didn’t we would explain that to MSHA and possibly have the sample validated. That is no longer an option.

    Yes these instruments do provide real time data which is very beneficial for wearers to change their position to decrease their level of exposure to respirable dust and yes they do actually practice said positioning even when not wearing the PDMs, though there are a large amount of technical issues with these instruments in which I have no answers for. In fact while searching for answers I came across this blog and decided to share a bit of what I have encountered with the PDM3700.

    Thank you for your comments and for your detailed description of several issues that you have encountered with the PDM3700. Your experiences, similar to those expressed by other mine personnel, will provide guidance on modifications needed to improve the performance of the PDM 3700 and/or the next generation of sampling instrument. NIOSH will forward your comments and concerns to the PDM manufacturer. In addition, we are encouraged to learn that miners are using the real time data to reduce their exposures, as this is a major benefit provided by the PDM.

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Page last reviewed: November 13, 2019
Page last updated: November 13, 2019