July 2, 2018 Celeste Monforton, DrPH, MPH 0Comment

An expert panel convened by the National Academies of Sciences, Engineering, and Medicine (NAS) put to rest assertions by the coal industry about the validity of a sampling device used to measure respirable coal dust.  The panel’s report was issued last week following an 18 month study.

The coal industry complained that the continuous personal dust monitor (CPDMs), which is an integral part of a 2014 MSHA regulation to better protect coal miners from black lung disease, gives inaccurate results.  The industry claimed that the samples captured by the device were contaminated by rock dust which is used in underground coal mines to suppress explosions.  As a result, they argued, MSHA inspectors would be erroneously citing mine operators for violating coal mine dust limits.

The NAS panel, however, concluded this:

“Measurement of respirable coal mine dust concentrations include respirable rock dust particles, by definition.  However, it appears that complying with the rock-dusting requirements has not been a large obstacle to demonstrating compliance with the sampling requirements of the 2014 dust rule.”

At one time, the industry supported the development of a device that could continuously monitor respirable coal dust.  Their support lasted, that is, until such a device was ready to be deployed. Then the industry made up excuse after excuse about why the CPDM was a bad idea. I wrote in 2011 about the coal industry’s behavior on this topic.  The CPDM saga continued through to the NAS’s conclusion last week.

Following a 2011 proposal by MSHA to address black lung disease, coal industry lobbyists asked their friends on Capitol Hill to insert appropriations riders that barred MSHA from developing a rule that required CPDMs.  When MSHA eventually adopted a rule in 2014—one that mandated the use of CPDMs—the industry continued to sow doubt about the device’s accuracy.  While the industry challenged the rule in the U.S. Court of Appeals, they also had Republican lawmakers pestering MSHA chief Joe Main and mimicking the industry’s manufactured doubt about the CPDMs.  The chair of the House Appropriations Committee and three Republican colleagues told the MSHA chief that his agency had not “sufficiently considered the impact of rock dust composition” on mine operators’ ability to comply with the new coal dust regulation. They wrote:

“The sampling frequency mandated by the new rule in conjunction with the new mandated sampling technology (CPDMs) increases the likelihood for operators to be cited for contaminated, but otherwise compliant samples.  It appears the sampling technology (CPDMs) is not yet proven to effectively distinguish between rock dust and coal dust, meaning operators may be incorrectly cited for noncompliance based on false readings of the mine environment.  Further, it is unclear if the new rock dust will be more prone to become airborne in the mine environment, increasing the possibility of flawed results.”

Republican lawmakers also invited the coal industry to pile on its attack about the CPDMs in a public forum.  The National Mining Association Bruce Watzman testified in October 2015 before a subcommittee of the House Education and the Workforce Committee where he continued the tactic of raising doubt about the accuracy of the CPDMs.  The penultimate step was the mandate by Congress in the appropriations for fiscal year 2016 for NIOSH to sponsor a study by the NAS.

I don’t think the coal industry got what they wished for in the NAS report.  The expert panel quickly dismissed the industry’s simplistic critique of the CPDM. They then took a deep dive into dozens of topics related to respirable coal dust monitoring.  The panel did not shy away from acknowledging the resurgence of black lung disease in the U.S. It cautioned the industry and regulators from becoming complacent about addressing the epidemic just because a new regulation was adopted in 2014.

“Even though mine operators today are complying with regulatory requirements for monitoring conditions that affect miner health, these approaches may not guarantee that exposures will be controlled adequately or that future disease rates will decline.

A fundamental shift is needed in the way mine operators approach exposure control to continue progress toward eliminating coal mine dust-related lung diseases.”

Among other recommendations, the expert panel says CPDMs should be complemented with continuous dust monitoring in fixed locations (i.e., area monitoring); medical histories should include much more detailed information about a miner’s occupation, such as duration of work at the coal face; and more research is needed on the relationship between dust particle characteristics and respiratory disease.


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