For example, NIOSH conducts research on  the causes of work-related diseases and injuries; researches, develops,  and tests new technologies and equipment designed to improve mine  safety; and recommends occupational safety and health standards, such  as the exposure limit for coal mine dust. In addition, to estimate the prevalence of lung disease among  underground coal miners and to study the relationship between miners’  lung disease and their level of exposure to coal mine dust, NIOSH  developed the National Study of Coal Workers’ Pneumoconiosis. There are two primary types of underground coal mining in the United  States: continuous mining and longwall mining. MSHA Did Not Use Recent CWP Trend Data as a Basis for Its Proposed Exposure Limit on Coal Mine Dust, Which Was Appropriate

Appropriately, MSHA did not use NIOSH’s surveillance data as the basis  for its proposed new coal mine dust limit, although the data served to  inform MSHA’s decision to take action. However, as we reported in August 2012, the data  MSHA used to support its proposal were from two reports, which relied on  six epidemiological studies, not the surveillance data. For example,  because the data do not include individual miners’ past exposures to coal  mine dust, they cannot be used to estimate disease risk for individual  miners. Experts Identified Various Approaches that Could Reduce Overall Coal Mine Dust Levels, as Well as Individual Miners’ Exposure to Dust

		Experts Identified Various Engineering Controls That Could Help Reduce Overall Coal Mine Dust Levels

Experts identified various engineering controls that could further reduce  the overall level of coal mine dust, but they said reductions would likely be  incremental. However, they noted that these  options would not help mines reduce the overall level of coal mine dust in  the mine environment, and therefore would not help mine operators  comply with MSHA’s exposure limit. Personal protective equipment  includes items such as respirators and air stream helmets. The experts also said that personal dust monitors could  be used to reduce individual miners’ exposure to dust because they  provide workers with real time data on dust levels in the area of the mine  in which they are working. The experts also noted that administrative controls could limit miners’  exposure to coal mine dust, although they do not control the overall level  of dust in the mine. Both agencies generally  concurred with the findings of the report, but provided no formal written  comments. We are sending copies of this report to the appropriate congressional  committees and the Secretaries of Labor and Health and Human  Services. Appendix I: Objectives, Scope, and Methodology

The objectives of our review were to: (1) determine the extent to which  the Mine Safety and Health Administration (MSHA) used recent coal  workers’ pneumoconiosis (CWP) trend data as a basis for its proposed  exposure limit on coal mine dust, and (2) obtain experts’ views on ways to  lower the level of dust in coal mines, including their associated  advantages, disadvantages, and cost. To address our first objective, we reviewed MSHA’s Notice of Proposed  Rulemaking, including the proposed exposure limit and related  documents, updated the literature search from our prior report, and  interviewed officials from MSHA and the National Institute for  Occupational Safety and Health (NIOSH) to identify recent data on the  prevalence of coal worker respiratory diseases. We also reviewed our prior  report and the analyses that supported it, and interviewed MSHA and  NIOSH officials to determine what role, if any, recent CWP trend data had  in developing the proposal to lower the exposure limit.
Why GAO Did This Study

Underground coal miners face the threat of being overexposed to coal mine dust, which can cause CWP and other lung diseases, collectively referred to as black lung disease. In October 2010, MSHA—the federal agency responsible for setting and enforcing mine safety and health standards—proposed lowering the exposure limit for respirable coal mine dust to reduce miners' risk of contracting black lung. In August 2012, GAO reported that the evidence MSHA used supported its conclusion that lowering the exposure limit on coal mine dust would reduce miners' risk of disease. However, some have questioned whether and how recent NIOSH trend data on CWP were used in developing the proposed limit.
In May 2013, GAO was asked to provide additional information on MSHA's proposal. GAO examined (1) the extent to which MSHA used recent CWP trend data as a basis for its proposed exposure limit, and (2) expert views on ways to lower the level of dust in coal mines, including their associated advantages, disadvantages, and cost. GAO reviewed MSHA's proposal and related documents; updated a previous GAO literature search; interviewed MSHA and NIOSH officials; and, with the help of the National Academies, convened a group of experts knowledgeable about underground coal mining and methods for reducing coal mine dust. GAO is not making any recommendations in this report, and MSHA and NIOSH both generally concurred with the findings.

What GAO Found

The Department of Labor's Mine Safety and Health Administration (MSHA) appropriately did not use recent trend data on coal workers' pneumoconiosis (CWP) as a basis for its proposal to lower the permissible exposure limit for respirable coal mine dust. These recent data from the Department of Health and Human Services' National Institute for Occupational Safety and Health (NIOSH) are inappropriate for this purpose because they do not include the types of detailed information about individual miners needed to estimate the likelihood that miners would develop CWP at different exposure levels, such as historical dust exposures. MSHA primarily based its proposed new limit on two reports and six epidemiologic studies, which each concluded that lowering the limit on exposure to coal mine dust would reduce miners' risk of developing disease. MSHA's proposed coal mine dust limit was supported by these reports and studies because, unlike recent CWP trend data, they included information needed to conduct a reliable epidemiological analysis of disease risks associated with different levels of exposure to coal mine dust.
Experts identified various approaches that could incrementally reduce overall coal mine dust levels as well as individual miners' exposure to dust. They said that air and water are the primary engineering controls used to reduce overall coal mine dust levels in the mine environment, which are used in various mining equipment, such as sprays. The experts also said that no one technology or approach would result in substantially lower dust levels, but instead could have a cumulative impact if used together. They also noted that all the approaches may not be effective in all types of mines, and that there are a number of cost drivers that would have to be considered, such as machine maintenance and training. The experts also identified other approaches, such as personal protective equipment and administrative controls, which could reduce individual miners' exposure to dust. Personal protective equipment includes respirators and air stream helmets; administrative controls include rotating workers and using remote control devices. However, they noted that these approaches would not help mine operators comply with MSHA's exposure limit because they would not reduce the overall level of coal mine dust in the mine environment.