Published in the August 2008 Coal USA Magazine

While “black lung” is a term long rooted in US mining’s history, coal workers’ pneumoconiosis is still an industry health issue and is currently the leading cause of occupational-illness-related deaths among coal miners in the nation.

To help combat the issue and provide an outlet to receive real-time answers to the question of exposure levels in various areas of a mine, the National Institute for Occupational Safety and Health along with the Bituminous Coal Operators’ Association, United Mine Workers of America, National Mining Association, Thermo Fisher Scientific and the Mine Safety and Health Administration joined efforts to develop the PDM.

A group of NIOSH researchers, including Jon Volkwein, recently took the project a step further by providing the unit to miners working underground and documenting their reactions to the device as well as how they made use of the information provided.

“The PDM has been field-tested at 10 mines and found to be at least as accurate as samplers currently in use,” the group said in a report released in February of its past evaluation work. “If miners know how to properly use the information that PDMs are capable of providing, they may be able to make adjustments to their workplace or work procedures that will reduce their exposure to respirable coal dust.

“There seems to be great potential. However, no one knows precisely how miners performing a wide variety of tasks and jobs are actually going to use this new information to reduce their exposure to dust.”

In hopes of finding that potential on a larger scale, the group looked at individuals who put the unit into use for four weeks, and conducted evaluation interviews with 30 miners and seven mine safety staff members who kept it at their sides throughout that time.

The researchers selected several underground job functions to represent major mining categories, including shuttle car operators, longwall shearer operators, mechanics, section foremen, scoop operator, operators of continuous miners, bolters, electricians and facemen.

The miners selected had varying levels of experience, from one with less than two years in mining to 19 who had more than a decade logged underground. They also varied in age: six who were less than 30, six between 30 and 39, 12 between 40 and 49, and six miners who were 50 or over.

The researchers pointed out that the mines chosen were working in higher seams, with three of the mines located in West Virginia and one in Utah.

Among their findings, the researchers found that the workers included in the test looked at their units several times, with some offering a number that ranged from one to 20 but averaged six. Twenty of the workers responded that they looked at the unit every day, while eight reported checks most days, one reported “a few days” and one said “never”

As each PDM includes several different screens to review information about dust concentrations – such as MC0 for exposure over the past 30 minutes, CUM0 for a cumulative total since shift start, and PROJ for projected exposure during the shift – researchers then asked the wearers how often the initial screen was viewed. Most said three times a day or more (20), while nine responded that the screen was looked at once a day or more.

The same number of test subjects also reported reviewing the unit’s bar chart feature, as each bar represents concentrations over 30 minutes. Six of the individuals looked at the feature at least once a day, three a few times a week and one less than once weekly.

A vast majority of the 30 workers said that they recognized fluctuations in their numbers throughout their workday. Of those who did (27), all said the factors that made those figures change were clear to them and several were surprised by the dust levels seen on the display.

“Seventeen of 30 replied yes,” the group noted. “Those who said yes were asked to recall the most recent time this happened and to explain what they were doing when they noticed the unusual reading. The types of activities they mentioned were returning from tailgate on longwall; cutting coal with continuous miner; cutting rock with continuous miner; operating shields on longwall; riding the mantrip; operating scoop in the return; and roof bolting.

“All but one of these 17 miners said that they were surprised by how high the numbers on their PDM were. One miner who was cutting rock with a continuous mining machine said he was surprised because the numbers were not as high as he thought they would be.”

The NIOSH researchers said that the feedback they received in their testing was important for helping workers realize that dust controls are critical while facilitating the future of the technology that can potentially help prevent black lung in the future.

“A major strength of the NIOSH study is that the information was obtained from people who regularly work underground and who will actually be using this new technology,” the group said. “Their assessment of the potential for using PDMs to protect their lungs should most definitely be considered as an informative and insightful source of information.”

While it was noted that the PDMs were not utilized long enough at the test mines to provide evidence for its institutionalization, the group got the reaction they were seeking: most miners paid attention to PDM feedback and made efforts to reduce their dust exposure.

“The empirical evidence concerning the validity of the model is rather limited [but] it is hoped that the findings from this study will serve to stimulate additional research and will raise more questions about the role of feedback as a determinant of self-protective worker behavior,” the group said.