One Hundred Years of Federal Mining Safety and Health Research

esearchers reanalyzed data from the earlier ALFORD survey of surface coal mines from the early
1970s, looking specifically at drill crew members and excluding those with prior underground
experience. Pneumoconiosis prevalence among drill crew members was found to increase from
1.6 percent for those with less than ten years of drilling tenure to 15 percent for those with 20 or
more years’ experience. The NIOSH researchers concluded that “The belief that only coalminers
who work underground have an appreciable risk of developing pneumoconiosis needs to be
modified” [Banks et al. 1983].
In the mid-1980s, NIOSH carried out a new survey of the respiratory health status of surface coal
miners [Amandus et al. 1989]. The survey found that pneumoconiosis was more prevalent among
drillers (16 percent) than among others who had no drilling experience ( 80 percent) than among surface miners in other
jobs.
As part of this same effort, NIOSH later analyzed MSHA data from 1982-86 [Piacitelli et al.
1990], finding that over 75 percent of the quartz samples for drillers exceeded the respirable silica
PEL. In a listing of the ten jobs with the highest average respirable quartz exposures, the first three
jobs were “highwall drill helper,” “highwall drill operator,” and “rockdriller,” and the average
concentration for these three together was double that of the next highest job on the list (“bulldozer
operator”).
NIOSH increased its efforts on this issue, developing engineering controls and other
recommendations to reduce occupational silica exposures, e.g., improvements to dust collector
on drills used by highwall drill operators, and cab-enclosure filtration systems. NIOSH had
earlier produced an Alert warning employers and employees of the severe risk of improper
operation of drilling equipment [NIOSH 1992].
With a collaborative NIOSH-MSHA-OSHA “Silica: It’s not just dust!” prevention program in
the 1990s, MSHA undertook enhanced efforts to reduce occupational exposures to silica and
eliminate the incidence of silicosis, carrying out special industry-wide inspection “sweeps” of
surface mines and establishing improved regulations for more effective enforcement of dust
control on drilling rigs at surface mines. These new regulations required effective drill dust
control regardless of dust exposure level [30 CFR § 72.620].
6.2.5 Diesel Particulate Regulations
Underground miners have routinely been exposed to very high concentrations of diesel
particulate matter (DPM), much higher than any other occupation. In 1998, MSHA proposed
two diesel rules—one for coal mining, the other for metal/nonmetal mining. The coal rule set a
staged implementation limit on DPM emission ending at 2.5 g/hr for heavy-duty equipment, and
this rule could be met by the use of MSHA-approved filters in the exhaust system. The metal
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