In a notice, the Mine Safety and Health Administration (MSHA) says it is beginning a retrospective study on how effective its 2014 final rule has been in lowering the exposure of underground and surface miners to respirable coal dust.
MSHA states that it is requesting information from stakeholders in a number of areas to assist in forming the framework of the study. The agency says it is interested in the engineering controls and best practices mine operators find most effective to achieve and maintain the required respirable coal mine dust and quartz levels—particularly those practices that can be replicated throughout coal mines nationwide to achieve similar results. Comments must be received by MSHA by or postmarked no later than July 9, 2019.
The 2014 rule was a major rewrite of MSHA’s existing standards on miners’ occupational exposure to respirable coal mine dust. Among its provisions, the action lowered the preexisting exposure limits; provided for full-shift sampling; redefined the term normal production shift; and added reexamination and decertification requirements for persons certified to sample for dust and maintain and calibrate sampling devices.
Also, the rule provided for single-shift compliance sampling by MSHA inspectors; established sampling requirements for mine operators’ use of continuous personal dust monitors (CPDMs); required operator corrective action on a single, full-shift operator sample; changed the averaging method to determine compliance on operator samples; and expanded requirements for medical surveillance of coal miners.
While the rule was issued under the Obama administration, in February 2018, David G. Zatezalo, the assistant secretary of Labor for Mine Safety and Health appointed by President Donald Trump, told a congressional committee that MSHA has no plans to revise the current requirements.
All rule requirements were effective as of August 1, 2016. One of the objectives of the retrospective study is to compare respirable dust samples taken before and after the effective date. MSHA notes that new miners hired after the effective date are the only cohort of coal miners who are unaffected by exposures that occurred before full implementation of the rule. The agency says it has analyzed more than 250,000 respirable dust samples taken by mine operators who use CPDMs and by MSHA inspectors who use a gravimetric sampler. The analysis shows that more than 99 percent of these samples were in compliance with the respirable coal mine dust standards.
The major challenge of the retrospective study will be determining the occurrence of diseases caused by exposure to coal dust before the rule went into effect. Some of the diseases, such as coal workers’ pneumoconiosis and silicosis, have a significant latency period.
“Due to the latency between exposure and disease, MSHA likely will not be able to evaluate fully the health effects of the rule for a decade or more,” states the MSHA.
Also, in accordance with a request from Congress, the National Academy of Science (NAS) is currently studying monitoring and sampling approaches for informing underground coal mine operators’ decision-making regarding the control of respirable coal mine dust and mine worker exposure. Congress also directed MSHA to provide assistance and necessary data to the NAS for its study, which, MSHA says, it has done and continues to do when requested.
“MSHA will evaluate the results of the NAS study after the report is final,” says MSHA.
The request for information was published in the July 9, 2018, Federal Register (FR).