Research Programs of the U.S. Bureau of Mines: First Assessment, 1994 (1994)

The Committee on Research Programs of the U.S. Bureau of Mines established a panel to conduct an in-depth review of the bureau's occupational health research program. The panel reviewed materials provided by the bureau, briefed and interacted with researchers during visits at the Pittsburgh Research Center and the Twin Cities Research Center, and received input from a broad range of users.

The Federal Coal Mine Health and Safety Act of 1969 established mandatory health and safety standards to protect the nation's coal miners. The Federal Mine Safety and Health Act of 1977 extended the standards to protect other miners. In Title II of the act (Interim Mandatory Health Standards), the purpose of the title is identified:

... to provide to the greatest extent possible, that the working conditions in each underground coal mine are sufficiently free of respirable dust concentration in the mine atmosphere to permit each miner the opportunity to work underground

during the period of his entire adult working life without incurring any disability from pneumoconiosis or any other occupation related disease during or at the end of such period.

The title prescribes the respirable dust standard in the coal mines as follows:

... each operator shall continuously maintain the average concentration of respirable dust in the mine atmosphere during each shift to which each miner in the active workings of such mine is exposed at or below 2.0 milligrams of respirable dust per cubic meter of air.

The title also specifies medical examinations, dust from drilling rock, dust standards when quartz is present, and noise standards. It also specifies how to make measurements to be in compliance with the act. In Title IV, the Congress established a Black Lung benefits program. In Title V, the act directed the secretary of the Department of the Interior and secretary of the Department of Health and Human Services to conduct studies, research, experiments and demonstrations to achieve the act's intended purposes. Also, Congress authorized funds for these activities.

In summary, the control of health hazards in mines at the federal level incorporates several agencies, including the Mine Safety and Health Administration (MSHA, Department of Labor), the National Institute for Occupational Safety and Health (NIOSH, Department of Health and Human Services), and the U.S. Bureau of Mines, through inspections, enforcement, and research and development on scientific, engineering, and medical issues. In addition, several states have their own agencies for assessing and controlling the health and safety hazards. The committee's occupational health panel reviewed only the bureau's occupational health research program authorized under Title V of the 1977 act.

The bureau's research program is organized into three divisions: Health, Safety, and Mining Technology (HSMT); Minerals and Materials Sciences; and Environmental Technology. The occupational health program element is one of the six elements of the HSMT division. According to HSMT 's long-range plan², health research addresses issues

... where there is not sufficient economic incentive for individual mining companies to perform the research, but where the potential benefit to the Nation justifies federal involvement. Focus is on eliminating the hazards before they develop, on providing technology for inherently safer and more productive mining systems, and on providing adequate attention to the human element in order to assure safe and efficient interaction among mine workers, the environments they work in, and the equipment they operate.

Much of the current research within the occupational health element concentrates on reducing worker exposure to respirable mine dust, diesel engine exhaust emission, and noise. The remaining research within this element focuses on developing sampling and measurement technologies for respirable dust, diesel engine exhaust emission, and noise. Some of the research, particularly the sampling and measurement research, directly supports the mandated functions of MSHA and NIOSH.

Except in cases of in situ leaching, mining requires the breaking and transporting of rock, which invariably results in the generation and entrainment of dust. Airborne dust problems can be acute in the confines of underground mines. Dust, in particular quartz dust, is generated in many surface mining operations and, for the most part, exposure is below compliance levels. However, instances of overexposure are still a concern for some surface mining jobs (e.g., drill operators, bulldozer operators).³

Respirable coal mine dust, when deposited and retained in the nonciliated air spaces of the lungs, can cause coal workers' pneumoconioses⁴ (often referred to as black lung disease). Prolonged exposure to coal mine dust also contributes to the occurrence and severity of chronic bronchitis, emphysema, and loss of ventilatory function. ⁵ Compliance with the 2 mg/m³ standard has been reached in most coal mines by (1) adaptation of existing technology to control, suppress, and collect respirable coal mine dust and (2) use of administrative and personal protection

controls to reduce exposure of workers. A 1980 NRC report⁶ provides basic information on the technologies used. Some of the bureau's occupational health research over the past 10 years has refined some of these technologies.⁷ A significant change in the past decade has been the growing contribution of longwall mining techniques to underground coal mine production. Longwall mining methods yield higher productivity per shift but usually result in higher dust production. The major emphasis of the bureau 's research in coal mine dust control is on longwall coal mining.

Besides coal dust, other dusts in mine atmospheres are of concern to the health of miners. In all types of mines, respirable quartz dust is a major concern because it can cause silicosis and may also contribute to the risk of lung cancer.⁸ The quartz dust issue is also related to milling and handling, particularly in crushed stone operations.

Miners working underground where diesel engines are used are exposed to a wide variety of exhaust, including noxious gases (CO, CO₂, NO, NO₂), numerous hydrocarbons, and diesel particulate matter (DPM). DPM are elemental carbon particles (<1 µm in diameter and thus respirable), often aggregated, onto which numerous hydrocarbons are adsorbed. Many of these hydrocarbons are known carcinogens (e.g., benz-a-pyrene, anthracene). NIOSH,⁹ the International Agency for Research on Cancer,¹⁰ and the Environmental Protection Agency¹¹ consider whole diesel exhaust to be “potentially” or “probably” carcinogenic. Bureau research has shown that DPM exposure in mines ranges from <0.2 mg/m³ to > 1.2 mg/m³, which

is two to three orders of magnitude higher than levels measured in ambient air. The relative importance attached to coal and diesel dust generation and entrainment versus airborne dust control is discussed below as a separate issue.

Other potentially harmful materials also can be associated with mining operations. For instance, the amount of in-mine radon and radon daughters can be a concern in certain types of mines (radon exposure in underground coal mines is usually negligible) as are other gases, such as carbon monoxide. Other materials of concern include hexavalent chromium, Cr(VI), a recognized carcinogen, which is generated during welding with stainless steel filler metals.

The 1969 act requires each coal mine operator to take, on a regular basis, accurate samples of miners' exposure to respirable dust. The purpose of these samples is to determine compliance with the exposure limit. MSHA also takes samples for evaluating the operator's dust control procedures, identifying which occupation on each mining section is the “designated occupation,” and evaluating the amount of quartz in respirable dust.

MSHA is currently reviewing its program for monitoring respirable dust. An MSHA task force,⁷ to which the bureau provided technical assistance, recommended the following long-term improvements:

• accelerated research to evaluate existing state-of-the-art technologies having the potential to be used in the development of a fixed-site underground coal mine monitor;

• an accelerated research program to develop instrumentation for continuously monitoring the parameters (ventilating air quantity, water consumption, entry velocities, etc.) used to control dust;

• a research program to develop a device for measuring full-shift personal respirable dust exposures and for a hand-held detector to determine the efficacy of methods used to control dust; and

• the development of new or improved dust control technology, with special emphasis on dust control methods for high-production longwall mining units and other mining operations.

Because of its compliance oversight of mining operations, MSHA has strong interests in a more reliable dust exposure monitor deployed by mine operators. These interests are important to the development of the bureau's research program through various agreements (discussed later).

Control of workers' exposure to respirable coal mine dust can be achieved in two ways: (1) personal protection of the individual miner through the use of protective devices or other (e.g., administrative) means that reduce the dust concentration in the inhaled air to below mandated levels (i.e., an aspect of the so-called administrative control) and (2) reduction of the dust concentration in ambient air to below the mandated level (i.e., environmental control.) Reduction of exposure to respirable dust using respirators has been a low priority for the bureau in large part because feasible engineering controls are viewed as more effective and because the 1977 mine act indicates a preference for environmental controls.

In the area of noise, work has been done on personal protection through earmuffs and other devices. Although there is emphasis on noise reduction in the mine environment through technological solutions to noise from of specific equipment or mining procedures,¹² it appears that noise will continue to be near current compliance levels, which is currently at a level of 90 decibel average (dBA) ¹³ per shift.

Table A.1 gives titles of the current occupational health projects according to topic and gives an aggregated annual budget authority.

The current specific objectives of the bureau's research in respirable mine dust, as stated in the HSMT long-range plan,² are to

• develop methods and make the technology available to the industry to increase compliance on continuous miner sections operating under more stringent dust standards due to the mine air containing respirable-size silica particles by 1994;

• design effective techniques to reduce the respirable dust generated by the advanced, extended-cut longwall mining operations by 1996; and

• identify the interaction between dust control parameters and develop and evaluate a continuous monitoring system capable of determining the effectiveness of the parameters by FY1996.

The U.S. Bureau of Mines has maintained a research portfolio on respirable mine dust (principally coal mine dust) for decades. The current research programs can be broadly categorized into three components: dust generation, dust control, and measurement. Individual projects change as results yield new insights and as new regulations are adopted that are designed for increasing worker protection. The objective of the bureau's research has been to devise and promote practical and low-cost technologies that result in lower dust exposure. Specific projects have included (1) research to develop technologies to reduce dust, (2) surveying mines to identify work practices that could result in lower dust exposure, (3) developing improved sampling methods to assess the effectiveness of new technologies and their dust generation/control, (4) exploiting positive trends in equipment development, and (5) assessing the applicability of new technologies developed for other purposes. Over the past 15 years the program has developed dozens of refinements in the technologies to reduce dust on longwall and continuous miner sections. Results of this research have been adopted by mine operators and have played a large part in allowing longwall mining operations to maintain compliance despite significantly increasing production levels.¹⁴

A review of the past 15 years of the bureau's Technology News Bulletins indicates that the dust generation and control issues addressed topics including (a) ventilation and air handling processes, (b) the rock breaking processes at the coal face, (c) drilling methods and roof bolting, (d) suppression of dust at the face through water sprays (and foam) and, (e) methods of removing material from the face. As an example, refinements on the effects of a variety of additives (anionic surfactants and water-soluble polymers) to the water sprays for dust control have shown some promising results. The bureau has reported that tests indicate over 40% reduction in respirable dust from longwall operations with additives versus no additives in the spray. The associated extra cost is projected to be about 5 cents/ton (longwall production) of clean coal. Field tests are continuing on the water spray additives.

This research is aimed at reducing worker exposure to respirable dust, primarily silica dust in mineral processing plants. Research under this program was requested by other federal (NIOSH) and state (e.g., Nevada) agencies because of health risks and lack of appropriate technology. This program area is scheduled to be completed in September 1996. For the past 10 years the bureau has had a series of projects related to bagging and handling operations and ventilation in silica processing plants, the results of which have markedly lowered worker exposure to dust. There is also research related to dust control systems during dumping at primary crushers; this is essentially a water spray system designed to suppress dust as rock is unloaded from a truck.

A 1980 NRC report, Measurement and Control of Respirable Dust in Mines,⁶ concluded that, “since current sampling technology [gravimetric] is adequate for measuring concentrations of respirable coal mine dust for compliance purposes, further research in this area need not be pressed.” For the past dozen years the bureau heeded this advice; additional work on monitoring principles was weaned from the bureau's research program. However, the bureau continued development (largely through a research contract with GCA Corporation) of the MINI-RAM (Miniature Instantaneous-Readout Aerosol Monitor) and engineering adaptations of existing technologies.

In 1992 the MSHA Coal Mine Respirable Dust Task Force⁷ concluded that, “continuous monitoring ... offers the best solution for improving the dust enforcement program” and recommended “an accelerated research program to develop a fixed-site monitor capable of providing continuous information on dust levels to the miner, mine operator, and to MSHA if necessary. ” Even though the concept of a fixed-site, continuous dust monitor remains controversial, the bureau responded to this recommendation by accelerating its research program to meet the needs enunciated by MSHA; additional funds were specifically appropriated in 1992 by Congress for this effort.

The bureau's program in developing suitable technology for a continuous dust monitor is organized in three tasks: (1) evaluation of existing technologies for improving continuous dust monitoring, (2) developing prototypes of continuous dust monitors using promising technologies, and (3) conducting collateral research to support development of continuous dust monitoring concepts.

Three principles for continuous dust monitors are currently being assessed: (1) the tapered element oscillating microbalance (TEOM); (2) the ß-ray attenuation

meter; and (3) the vibrating filter element, which is based on either a laser-microbalance or laser-scattering principles. A prototype of the TEOM, along with a ß-attenuation mass monitor, is being evaluated in the laboratory with mixtures of respirable coal dust and diesel exhaust aerosols as a function of relative humidity.

The current specific objectives of the research in diesel engine emission control, as stated in the HSMT long-range plan² are:

• a ... diesel engine filter successful in reducing exhaust soot will be integrated with specifically formulated catalysts to control the gaseous contaminants in the exhaust of engines used in underground mines by 1994; and

• investigate the alternatives to mobile, diesel-powered mine vehicles that offer advances in air pollution and energy utilization by 1994.

During the past dozen or so years, the bureau has undertaken several projects related to diesel emission control and monitoring. Initial research provided analytical evidence related to maintenance and emissions. Other past research focused on exhaust control and filtration systems and fuel additives and catalysts.

Current research continues to focus on emission controls, fuels, and monitoring. The research ranges from evaluation of the literature on other developments and progresses to laboratory screening to full-scale laboratory testing to in-mine evaluation of a control technique or fuel. The current projects are shown in Table A.2 as a function of the evaluation process. Projects evolve from a literature review through the ultimate in-mine evaluation phase.

Noise in proximity to mobile transport equipment and mineral extraction operations is in many cases so high that many mining and processing operators can meet the MSHA maximum noise exposure levels only by rotating workers from noisy operations to those that are less so. This is an example of administrative controls being used to remain in compliance. The current regulations are 90 decibel average (dBA) for eight hours, with a 5 dBA tradeoff (at 95 dBA, cut exposure in half, to four hours; maximum = 115 dBA). The bureau's research on noise has fallen into two areas:

1. Research that focuses on efforts to lower noise levels by assessment and modification of equipment and methods used in mining operations. Activities have included drilling techniques and bit placement, use of noise control measures to reduce the noise levels from mine ventilation systems, and use of a variable-speed coal mine conveyor and designs to reduce overall noise levels. Computer modeling of noise sources has led to suggestions for placement of various equipment within a mining operation.

2. Research that evaluates the effectiveness of personal protection devices and ideal and nonideal deployment of hearing protectors. Some of the important factors are facial hair, safety glasses, head movements, and lack of training.

The U.S. Bureau of Mines is involved in the development of an industrial hygiene program that includes research on nontraditional pollutants and radiation hazards. This is largely in response to a 1989 proposed set of regulations by MSHA concerning a large range of chemical agents and air contaminants. The present emphasis of the bureau's activities is on monitoring, identification, and control aspects of many of these MSHA identified chemical agents to provide information for sound and technologically feasible rule making. Increased activity in this area should

be expected, particularly under the auspices of the Memorandum of Agreement (MOA) between the bureau and MSHA.

The bureau's radon program is the only occupational health project conducted out of the Denver Research Center (DRC). It is primarily aimed at measuring and controlling radon daughters in metal and nonmetal mines. Important objectives of current emphasis, as stated in the long-range plan, are (1) maintenance of a radiation calibration facility to evaluate radiation hazards in high-risk mines, and (2) monitoring and evaluation of mine radiation hazards to support MSHA's initiatives.

The panel reviewed staff, facilities, and funding levels to assess research capabilities; its findings are summarized in this section.

The U.S. Bureau of Mines staff for research in respirable mine dust, diesel emissions, noise and industrial hygiene consists of professionals with degrees in engineering, public health, and basic science. The research programs are concentrated primarily in the Pittsburgh Research Center (PRC) and the Twin Cities Research Center (TCRC). The bureau staff at each research center reports to the center's research director. According to the bureau, plans¹⁵ (beginning in FY1995) are for research staff to report along lines of research focus. The PRC will become the center of management focus for all areas of occupational health research. Currently, the bureau does not plan to budget for relocation of occupational health research staff members working at the TCRC to duty stations at the PRC. Two main reasons exist for this decision: staff members are pursuing interdisciplinary projects in areas outside the occupational health focus, given current program funding levels, relocation costs for equipment and people would be so high that reductions in overall bureau staff levels might be required. A third reason is concern for the possible disruption of the diesel work, which currently enjoys a strong working relationship with the University of Minnesota.

A total of 45 engineers, scientists, and health professionals comprise the occupational health research staff, with 24 at PRC, 19 at TCRC, and two at the DRC. Any

one of these individuals is or may be a principal investigator for a specific research project. A portion of their time is typically allocated to one or more ongoing research projects. At DRC there are two professionals, one with a Ph.D. (nuclear physics), who work on the radiation and radon project. At TCRC there are three Ph.D.s (two in physics and one in public health), six individuals have master 's degrees (in science or engineering), three are working toward completion of a master's degree, and the remainder have bachelor's level education. At PRC there are two Ph.D.s (one in physics, the other in engineering), nine individuals have master 's degrees, and the remainder have bachelor's degrees. Several individuals at both laboratories have dual degrees at either the master's or bachelor's level. In the areas of generation, control and measurement of respirable mine dust, diesel emissions, and noise control and protection, the mix of degrees at TCRC favors basic research, whereas PRC is directed more toward applied research.

The bureau supports student research by providing four-week cooperative programs for summer students at the TCRC, and postdoctoral fellowships through the National Research Council at the Denver center. The Pittsburgh center has also sponsored student researchers, and many of its research staff were recruited from this program.

Research is carried out primarily at the facilities in Pittsburgh and the Twin Cities, both of which have a campus-like atmosphere. Both centers have ample space to carry out their occupational health-related research.

At the PRC the bureau has a fully instrumented measurement and analysis laboratory to support research in mining noise control. Facilities include a reverberation chamber that meets American National Standards Institute specifications for use in conducting sound power measurements; its size (44,000 ft²) is adequate to accomodate most mining equipment and a variety of simulated mine operations. There is also an anechoic noise test facility. These facilities are unique within the bureau and are comparable to other leading research facilities throughout the world. There are also facilities for assessing techniques of coal mine dust suppression and control. There are two full-scale experimental chambers (one to simulate a standard continuous miner operation; the other a longwall mining operation) in which the atmosphere and dust content can be carefully controlled and monitored. Most of the bureau's work on optimization of ventilation, scrubbers, and water sprays at the cutting heads has been performed using these controlled facilities. There are also two full-size experimental underground mines that permit a variety of tests (although less controlled) of

equipment and techniques of dust control in environments somewhat similar to actual mining conditions.

At the TCRC, laboratory facilities are present for testing cutting system model prototypes, including the development of equipment for linear cutting of coal. Experiments can be taken up to the mining test phase for these research projects. Facilities exist for measurement of dust and diesel aerosols. A variety of equipment, including computerized monitoring instrumentation, has been provided to the TCRC by industrial cooperators. In fact, TCRC has several industrial R&D partnerships (particularly in its diesel research); almost a quarter of TCRC' s operational budget is matched by contributions from outside cooperators.

The radon measurement and control project at the DRC is an in-house project to characterize radon at a noncoal underground mine so that information can be obtained on how to control mine worker exposure. The bureau staff accesses the underground mine during MSHA inspections and uses portable measurement equipment owned by the DRC. The DRC also operates the Twilight Mine, the only experimental underground mine facility in this country that provides an environment for calibrating underground radon measurement equipment. These facilities were used to produce the 1975 MSHA report on radon in underground mines.¹⁶ The interagency cooperation on this project reflects the history of the bureau when MSHA was organizationally included with the it.

Cooperative efforts are ongoing with several researchers at the Mineral Research Institute's Generic Mineral Technology Center for Respirable Dust. The center is connected primarily with the Pennsylvania State University and West Virginia University; several other universities in the mineral institute program also carrying out projects. The bureau considered the center to be part of its overall occupational health research. The center, in cooperation with the bureau, MSHA, NIOSH, and industry, addresses fundamental aspects of both scientific and medical issues of respirable coal mine dust through laboratory and in-mine investigations. Current research on engineering and scientific aspects of dust control includes projects on two-phase flow spray systems, scrubber design efficiency, intake air quality, source generation, dust characterization, particle charge effects, dust agglomeration, diesel emissions, and characterization and control. On the medical aspects, there are several projects (primarily at the Hershey Medical Center of the Pennsylvania State University) are on-going on molecular, cel-

lular, and nonhuman primate levels; several of these projects are being conducted in cooperation with NIOSH researchers and use NIOSH facilities as well.

Funding for FY1994 was $8.9 million for all areas of occupational health research, as mandated by Public Law 91-73. Of this amount, about $4.2 million was spent on respirable dust projects. (As a part of the mineral institute program, an additional $2.5 million was provided to the Generic Mineral Technology Center for Respirable Dust.) Spending allocations for respirable dust control are made in support of the commitments and requirements within the Memorandum of Understanding¹⁷ and the Memorandum of Agreement¹⁸ recently signed with MSHA. Within this total, about 18% supports projects related to study of how respirable mine dust is generated, about 54% supports projects related to control measures, and 28% supports research and development of measurement technologies.

Currently, the major thrust of the bureau's diesel research is to reduce diesel emissions in mines; funding allocations for diesel emissions research are about $1.85 million. About 75% of the funds are spent on diesel emissions control, which includes both filtration research and research and development on methyl soyate diesel fuels (a cooperative effort supported by the National Soy Development Association). The remaining funds are spent on development of aerosol measurement technologies, including a cooperative project with a manufacturer. Computerized measuring equipment and diesel engines have been provided by an industrial cooperator to bureau researchers to develop a certification process for measurement of diesel emissions.

Resource allocations for noise control total $500,000; of this, 40% supports projects related to noise reduction and 60% supports projects related to control measures. Measurement technology development is not currently supported, as the required instrumentation is available commercially.

Funding for industrial hygiene comprises $493,000, which is focused on radon measurement and control at the DRC and chemical agents in the mining environment at the TCRC.

The bureau has a formal research project selection process that includes solicitation of miniproposals from the research staff. These miniproposals are evaluated to determine those to be developed into more elaborate full-scale project proposals. The miniproposals provide a mechanism to evaluate research ideas without requiring excessive time to develop full-scale project proposals. Miniproposals are submitted annually (November 30) to the research director of a specific center. The bureau indicated to the panel that the researchers who prepare the miniproposals are often those most familiar with problems as they occur in mines. The miniproposals are not prepared in a total vacuum but are guided by the bureau's current long-range plan and the multiyear funding plan, which may target priority areas. The miniproposals are reviewed and ranked, first by a center's research director, then by the research division. During this process, MSHA personnel provide their perspective on the priority ranking of the miniproposals. About 30 miniproposals in occupational health are considered each year.

Each miniproposals is evaluated based on the following questions and criteria:¹⁹

1. Does it meet the objectives of the research program as defined in the long-range plan and the multi-year funding plan?

2. Does it meet the intent of administrative/organizational goals?

3. Could it be part of a potentially new budget initiative?

4. Does the proposed research duplicate ongoing research being done in the bureau or elsewhere?

5. Is it technically sound?

6. Would the results be readily adopted by the mining and minerals processing industries?

7. Would the private sector do the work needed to solve the problem?

8. Does the research have the potential to have significant impact on the industry or only marginal incremental impact? Do the anticipated benefits justify the costs? Is there potential for cost-sharing by industry?

Those miniproposals selected (about March 1) as having good probabilities of successful research and of being funded in the next fiscal year are then prepared as

full project proposals (in occupational health, six or seven are prepared each year), which are submitted to the bureau's associate director for research for final review. The proposals that pass this final review (four or five in occupational health) then have detailed work plans, authorizations, etc., prepared for initiation of the research once the final congressional appropriation is enacted. The bureau uses what it calls a “rackup” to provide a detailed record of a project. The rackup is the basis of the formal authorization empowering the research centers to carry out the research.

MSHA plays an active part in the selection process. This has recently been formalized by a MOU and a MOA between the bureau and MSHA, both dated March 18, 1994. (A similar though less detailed MOU between the bureau and NIOSH was agreed to in July 1978.) The MOU between the bureau and MSHA formalizes an explicit methodology for MSHA to communicate its research needs to the bureau, to help formulate specific research programs and projects using MSHA-identified needs, and presentation by the bureau of research deliverables generated from the list of MSHA needs. The MOU is, in essence, simply a statement of philosophy and approach; on the other hand, the MOA is an implementation agreement. The MOA states that

MSHA and the USBM will combine resources of both organizations into single joint task groups dedicated to the resolution of critical MSHA-identified technological problems. Each joint task group will be charged with the resolution of an identified problem within a specific time period and will be given extraordinary latitude in achieving the stated objective.

Within the context of the MOA, several activities are specified. Selected activities are given below:

1. [Both] will jointly plan and conduct studies to resolve critical problems identified by MSHA.

2. USBM will provide and manage its funding and staffing appropriate to the urgency of the problem.

3. MSHA will also provide such technical staffing of its own as is consistent with the identified problem, and required for its satisfactory resolution.

4. Staffing selections will be made jointly by MSHA and USBM, each agency obtaining the concurrence of the other that selections are compatible with the task, capable of providing needed support within established time frames, and supportive of the joint venture task group initiative.

   [Numbers 5 through 8 deal primarily with mine safety issues and are not dealt with here.]

9. If required to prove the feasibility of a product delivered by the joint task groups, USBM and MSHA will jointly reassess requirements and reallocate their respective resources to the extent possible, to full scale feasibility testing [emphasis added] of the developed product(s).

Each study under this MOA would be negotiated individually. The MOA has a two-year pilot lifetime, at which point the results will be reviewed for continuation, redefinition, or termination. The panel believes the MOA to be an attempt at being more responsive to short-term critical needs.

These agreements raise two concerns. First, what are their possible effects on the balances between short-term and long-term research and between fundamental and applied research? Although MSHA's overall statutory mandate remains the same from one administration to the next, different aspects of policy may receive greater or lesser emphasis; as such, MSHA's perceived research needs also could vary. Furthermore, when MSHA promulgates rules and regulations, it must consider feasibility. The bureau is not similarly constrained and may undertake research projects that have only a moderate chance of success but, after investigation, may provide attractive and feasible solutions to occupational health problems.

The other concern is that MSHA appears to already exert great influence on the input received by the bureau from its users. These agreements could result in a dominating role for MSHA in the direction of the bureau's occupational health research. Input of the research needs of other users—mine operators, labor unions, and NIOSH—should continue to be factored into the bureau's selection of future research.

Once a project is initiated, specific deliverables are negotiated for the following fiscal year. These include reports, technical papers, and cost evaluations. Milestones (completion of specific tasks) and decision points (redirection, expansion, contraction, termination) also are negotiated at this time (summer). Once the research is under way, there are semiannual (April 15) and annual (November 15) progress reports from the research directors to the associate director for research.

The directors of the bureau's research centers are primarily responsible for managing the research projects and evaluating their quality. Three types of formal reviews are conducted to provide feedback to the research centers: (1) The division staff evaluates the output of the research by reviewing the quantity, quality, and timeliness of manuscripts and other deliverables and by estimating the value of the research products. (2) An annual bureau/MSHA project review is conducted, which helps to

keep MSHA personnel aware of research objectives and progress and to transfer technology. MSHA provides written comments on the individual projects. MSHA also uses this meeting as an opportunity to identify future research needs. (3) Intensive area reviews provide periodic evaluations of research areas (elements or subelements) by bureau personnel who have no direct responsibility for the research that is being reviewed. This is an assessment of the research portfolio and progress of specified areas. The bureau intends that this latter type of review would be replaced by the reviews through the present NRC committee.

To allow emphasis on more fruitful projects and to encourage some risk taking, individual researchers typically work on three or more projects during a given period. In this way, if a project is terminated, it does not automatically create a personnel problem for an individual researcher. Working on multiple projects also tends to ensure optimum use of a researcher's time.

Input on the quality and applicability of the U.S. Bureau of Mines research in the area of occupational health was sought from the users of this research. A discussion²⁰ among personnel from industry, labor, and government regulatory agencies focused on a number of questions that were posed to the participants prior to the meeting at the PRC. Although there were some minor differences of opinions, there was near consensus in answers to each question. A summary of this discussion, organized around the questions, follows.

What do you think the mission of the U.S. Bureau of Mines is regarding occupational health?

The users concurred that the mission should be to monitor occupational health hazards and conduct research on eliminating (or greatly reducing) such hazards and/or identifying alternative approaches to mining that would reduce health risks to workers. The three principal thrusts of the bureau's current research—respirable dust, diesel emissions, and noise—were thought to be appropriate. Users also indicated that the bureau should (1) provide technical expertise to the mining industry to implement

methods and equipment for measurement and control of occupational health hazards, and (2) disseminate information and technology transfer related to the measurement and control of occupational health hazards.

How should users provide input into the selection of projects in the occupational health research program? What ways could users provide adequate feedback to the programs?

Users thought that a joint working group representing industry, manufacturers, labor, MSHA, and NIOSH should be formed to advise the bureau on directions of research. Feedback could occur through this group by it providing backup review of projects to help assure consistency in level of project quality and balance among the various research priorities.

What is your impression of the quality of the bureau's occupational health research and how has it impacted your activities and operations?

Users called the bureau's occupational health research outstanding. They felt that it has been the standard for the industry. From a strictly occupational health standpoint, one user stated that without the bureau's assistance the coal mining industry in the United States would not be where it is today.

What should be the future emphasis of the bureau's occupational health research program?

Users queried thought that diesel emissions are the first priority. Issues to be resolved include the acceptable particulate level, how and where samples should be taken, and what the long-term exposure effects are. In order, other areas of research are respirable dust, noise, and ergonomics research (this area is actually in the occupational safety program of the bureau's HSMT division and was not reviewed in this report).

Several mechanisms are used for the transfer of technology developed by the U.S. Bureau of Mines. These include internal publications, Reports of Investigations, Information Circulars, publication of papers in journals and proceedings volumes, patents, presentations at technical meetings, and open industry briefings. The bureau also maintains an electronic bulletin board to provide its research information. The bureau's Gopher can be accessed by Internet users. Available on this bulletin board are:

• bimonthly lists of publications (text less figures);

• CRADA opportunities information;

• environmental technology research;

• mining, health, and safety research;

• minerals and materials science research;

• software products of the bureau;

• technology newsletters (constantly updated); and

• technology transfer updates.

Concern was expressed about the length of time required for research results to be available to users. Information provided by PRC and TCRC indicate that the average length of time from the initiation of a project to some type of publication is about one year, but there is significant variance in this average. To assess the transfer of technology by publication, a list of publications in the bureau' s occupational health components was compiled (Table A.3).

The bureau's current research on occupational health problems can be broadly classified as (1) respirable mine dust, (2) diesel emissions, (3) noise, and (4) industrial hygiene.

The panel found that the bureau's research on respirable coal mine dust is problem focused and, usually, quite relevant to mining operations and occupational health concerns. In this area the panel concluded that greater efforts to reduce dust during the cutting process could be more effective in reducing dust exposure to workers than remediative efforts; however, both reduction and remediation are essential.

Research by the bureau on respirable mine dust can be divided into three general categories:

• control of dust generation,

• suppression and collection (e.g., scrubbers) of generated dust, and

• dilution of dust with ventilation air.

In the mine all three categories can be used together (and should be viewed from a systems approach) to meet prevailing health standards. Of these three the panel believes that dust control at the source is probably the most effective means of reducing miners' exposure to respirable dust.

Control of Dust Generation The bureau responded vigorously to recommendations in the 1980 NRC report⁶ and increased its research on “the fundamental mechanisms by which fragments are produced in coal mining; how some of these fragments in the respirable size become airborne; and the spatial and temporal characteristics of respirable coal mine dust atmospheres.” Subsequent research by the bureau and others has led to an increased understanding of the dust generation process. This knowledge has led the bureau to the initial development of a modified technology for cutting coal. Over the past several years the bureau has successfully demonstrated under laboratory conditions that linear and jet-assisted cutting technologies indeed reduce the amount of dust generated. Other research has shown that the use of polycrystalline diamond compact bits (both continuous miner and shearer bits) holds promise for more efficient cutting and reduction of dust in the process. The major shortcoming of much of this work is the lack of adequate testing of these technologies in actual mines. Major modifications of expensive mining equipment to test the linear cutting process will need close cooperation and commitment of the equipment manufacturers; whether there is the economic incentive for them to consider such modifications remains uncertain. Cooperation with equipment manufacturers for testing and possibly replacing existing drilling and mining bits with stronger polycrystalline diamond com-

pact bits should be encouraged as a method of reducing the generation of respirable dust, particularly since such modifications are not as major as that of the linear cutting technology. Until these developments are tested in the mine, their associated costs, problems, and potentially increased benefits of reduced dust generation will not be known. The panel found that the bureau should aggressively pursue partnerships, particularly with mining equipment manufacturers, that would result in actual field tests and demonstrations of different technologies.

Suppression and Collection of Respirable Dust The bureau has done an outstanding job in the past decade of developing scrubbers for the collection of respirable coal mine dust. These scrubbers have been readily adopted by the industry. However, one area where the scrubbers are not readily applicable is in longwall mining systems. The problem is one of the longwall mining system: (1) the clearances around the longwall machines are low, and simple placement of existing scrubbers on existing equipment is limited; (2) the ventilation stream for the equipment and miners is in the same direction; and (3) dust production rates are very high. Suitable scrubbers for other sources of dust in the mine (e.g., belt transfer points and crushers) should also be investigated. The panel found that there is a clear need for further development of scrubbers, particularly for longwall mining.

The bureau's projects to optimize the pressure and rate of water flow for dust suppression have met with moderate success. The bureau has done an excellent job of locating water sprays during the cutting process; however, additional work on the placement of sprays for longwall configurations should be pursued. Bureau research has also involved mixing chemicals (e.g., surfactants and polymers) with the water in the sprays that enhance dust suppression. The bureau's claim that 60% of all respirable dust can be suppressed using surfactants and polymers should be verified in the field, and final results, if encouraging, should be transferred to the industry. Because of the potential for success in decreasing respirable dust exposure to miners and fairly easy adaptation by industry, further research in these areas should be enhanced, particularly in-mine testing.

Ventilating Air Dilution of Dust The bureau's main contribution in this area has been in directing the air current and keeping dust confined to the area between the conveyor and the solid coal face. The methods developed largely by the bureau in the past decade have been very effective in room and pillar mines and in reducing the dust exposure of the shearer operators in longwall operations. As a general method for longwall dust control, ventilation is not very effective because it can keep the dust pushed against the face to only a certain extent and there are miners “downwind” of the dust stream. The bureau should continue, if not accelerate, its ventilation studies

related to longwall mining methods. One possible approach might be an air current along the face where the ventilation air can be divided into two streams—one by the face side that will be highly dusty and the other between the conveyor and the gob shields.

Research and development, largely prior to 1980, by the bureau “contributed significantly to reducing mine dust levels through the development of improved methods for dust measurement and control. ”⁶ The currently used filter cassettes in the personal dust gravimetric samplers (average exposure over an eight-hour shift) resulted from this research, albeit with improvements to make it more tamper resistant. In the past few years the bureau's efforts in this area have been accelerated due to requirements of MSHA⁷ and others. The present research concentrates on machine-mounted continuous monitoring of respirable dust in coal mines.

The panel could not make judgment as to whether the machine-mounted continuous sampling strategy being pursued is scientifically meaningful. Clearly, there is controversy in the existing sampling strategy. One of the problems is in the selection of a location on the mining machine for such instruments. There is a very high concentration gradient in the vicinity of the cutting machines, which varies from location to location and makes it impossible to get repeatable and reproducible data that can be relied upon for time averaging or any other statistical processing. The panel believes that a sound scientific rationale is needed for the respirable coal mine dust sampling strategy. Despite the efficacy of the present sampling strategy, the bureau is continuing work on instrumentation that might address MSHA's needs.

The bureau is evaluating the effectiveness of an improved version of a MINI-RAM. The initial MINI-RAM was never used because of unreliability in the mine environment over extended periods. However, the instrument 's “short-term measurement capability has the potential to identify dust sources, to determine when full-shift sampling should be conducted, and to provide immediate feedback on the effectiveness of modifications to dust controls.”⁷

The bureau is assessing the applicability of instruments based on three dust monitoring principles that might satisfy MSHA's needs: (1) the ß-ray attenuation meter, (2) the tapered element oscillating microbalance, and (3) the vibrating filter element meter, all of which are based on either laser-microbalance or laser-scattering measurements. Instruments developed to date based on these principles appear to have serious limitations when they are used in actual mining environments. The presence of moisture, vibrations, and heterogeneity of dust could compromise the reliability of the dust measurements; there are also calibration problems associated with each of these three principles being investigated. For instance, no evidence was presented that

these methods could distinguish between coal dust and silica dust. Some of the major limitations to these three methods might be overcome by additional work, but the panel was equivocal on such future developments. The panel found that efforts are needed to improve the reliability and precision of the existing personal gravimetric dust samplers, particularly making a sampler operational for 40 continuous hours.

Although determination of a safe level of diesel particulate matter (DPM) remains unresolved, the bureau's research efforts are relevant to both engineering control of DPM and DPM sampling and monitoring. This was echoed by the group of users the panel sampled, who gave this research area their highest priority.

Over the past five years the bureau has made significant contributions to the occupational health issues related to emissions from diesel-powered mining equipment. Most of the work has had a large industry cooperative component. Among the advances are diesel engine controls and maintenance guidelines that result in lower emissions, exhaust filters that reduce the airborne DPM, and specialty fuels and additives that increase engine efficiencies while also reducing DPM. Of note has been the substantial progress made in preventing excessive emissions of DPM using special fuels (e.g., soy-ester and fuel additives) but there is no viable substitute for standard diesel fuels at present. Emphasis, therefore, should be on scrubbing the exhaust in a liquid bath and collecting the DPM with a disposable dry paper filter. A combination of these two preventive measures is considered adequate.

Diesel-powered equipment and bureau-developed engineering control of DPM are finding wide practice, particularly in applications in metal mines. However, much of the diesel technologies are not easily transferable to coal mines. For example, in metal mines, catalytic converters can be used and carbon particles can be burned off the exhaust filters. In coal mines, because of the potential for methane in the ambient atmosphere, similar temperatures present a major safety concern. (As an example, because of this safety concern and the lack of regulatory guidelines, Pennsylvania has not issued any permits for the use of diesel-powered equipment in mines.) Adaptation of diesel technologies for use in coal mines should be a focus for future bureau research.

Considerable time and money have been spent on developing instruments to measure the DPM fraction of respirable coal mine dust. However, the sampling strategy

being used by MSHA, NIOSH, and the bureau, again, is not universally accepted. The issue is confounded by lack of standards and regulations for DPM measurements in mines. The current sampling strategy assumes that all dust particles in the mine below 0.8 µm in size are DPM. The strategy is based on studies of respirable coal dust that show a log-normal size distribution with a median size of 2.4 µm with an upper limit of about 7 µm. Below 0.8 µm there were very few coal particles in the studies. When DPMs are introduced, there were two peaks in the size distribution, one a submicron peak and the other around 2.4 µm. Analysis showed that virtually all the DPMs were captured in the <0.8-µm portion (based on the distributions, this is not to say that everything below 0.8 µm represents only DPM, nor does everything above 0.8 µm represent only coal particles). However, some unpublished measurements indicate that dust concentration measurements in nondiesel mines have shown a substantial portion of respirable dust below the 0.8-µm size.

The bureau's research on noise has identified several modifications to mining equipment that could lead to lower levels of noise exposure to workers. One example is the armored faced conveyors in longwall operations, which can be extremely noisy when there is little or no coal being carried; modifying the conveyor to have variable speeds dependent on load could reduce this noise. The panel reiterates its previous finding that partnerships with mining equipment manufacturers should be pursued to test noise reduction modifications in the mine environment.

The bureau staff estimated that implementation of research and engineering control could be effective in 5 to 10% overall noise reduction. If, in the future, the compliance standard is lowered, the bureau should give greater emphasis to research on engineering and personal protection methods of noise reduction.

With the exception of its radon program at DRC, the bureau's program in industrial hygiene developed in response to a 1989 proposed set of MSHA regulations on a large range of chemical agents. Although there has been no further action on these proposed rules, the bureau should maintain a level of expertise in anticipation of the need for such scientific input to MSHA.

1. The U.S. Bureau of Mines needs an effective mechanism to receive user input on its research program. Input should be solicited from qualified representatives from industry, labor, government, and academe to help the bureau maintain relevance and quality in the selection of its research projects through their longer-term strategic planning.

2. The panel found that the proposed centralization of the occupational health research activities at one site could result in increased scientific collaboration and focus. The Proposed Organizational Structure draft report21 has the Pittsburgh Research Center becoming the center of excellence or focus for all of the bureau's health and safety research. There was a strong desire on the part of the panel to avoid unnecessary disruption of the diesel research at TCRC.

3. The panel found that there is a need for closer contact and collaboration with the mining and equipment industries. These interactions will help the bureau select topics for high-priority research and accelerate technology transfer. Frequent technology transfer seminars, held in mining communities, would be helpful.

4. The panel found that timely dissemination of research results is essential. There is often a large time lag between the initiation of a research project and dissemination of the results. The bureau has been doing a relatively effective job of this within the occupational health areas, but continued attention to this end is desirable. There is often a longer time lag between the disseminated research results and their application; greater technology transfer would be helpful.

5. Before the end of the current term of the MOA with MSHA, the panel believes that the bureau should carefully assess the impact of the MOA on its overall mission and its ability to perform and deliver research that would benefit other users.

6. The panel believes that the bureau must strive to maintain, and upgrade where needed, the technical strength of the groups working on occupational health topics.