[Federal Register Volume 59, Number 34 (Friday, February 18, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-3591]


[[Page Unknown]]

[Federal Register: February 18, 1994]


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Part II





Department of Labor





_______________________________________________________________________



Mine Safety and Health Administration



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30 CFR Part 56, et al.




Air Quality: Health Standards for Abrasive Blasting and Drill Dust 
Control;



Final Rule
DEPARTMENT OF LABOR 
Mine Safety and Health Administration
30 CFR Parts 56, 57, 58, 70, and 72 
RIN 1219-AA48 
 
Air Quality: Health Standards for Abrasive Blasting and Drill 
Dust Control 
AGENCY: Mine Safety and Health Administration (MSHA), Labor.

ACTION: Final rule.

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SUMMARY: This final rule addresses abrasive blasting and drill dust 
control at all metal and nonmetal and coal mines. The final rule 
retains existing requirements for rock drilling operations at metal and 
nonmetal mines and establishes new requirements for rock drilling 
operations at surface coal mines and surface work areas of underground 
coal mines. The final rule also revises existing requirements for rock 
drilling operations at underground coal mines. In addition, it 
establishes new specific standards for abrasive blasting operations at 
coal mines and expands existing provisions at metal and nonmetal mines.

EFFECTIVE DATE: April 19, 1994.

FOR FURTHER INFORMATION CONTACT: Patricia W. Silvey; Director, Office 
of Standards, Regulations and Variances; MSHA; (703) 235-1910.

SUPPLEMENTARY INFORMATION:

I. Background

    On August 29, 1989 (54 FR 35760), MSHA published a notice in the 
Federal Register inviting public comment on a proposed rule on air 
quality, chemical substances, and respiratory protection in mining. The 
proposed rule addressed means of controlling exposure to hazardous 
substances, permissible exposure limits, exposure monitoring, dangerous 
atmospheres, respiratory protection, carcinogens, asbestos construction 
work, drill dust control, abrasive blasting, and prohibited areas for 
food and beverages. This final rule addresses abrasive blasting and 
drill dust control, which are the first of these sections to be 
completed.
    In comments on the proposal, the Agency received requests to hold 
public hearings. In response, the Agency held three sets of public 
hearings on the proposed rule. The first set of public hearings, which 
specifically addressed abrasive blasting and drill dust control, was 
held in Denver, Colorado, on June 4, 1990, and in Pittsburgh, 
Pennsylvania, on June 7, 1990. Following the public hearings, the 
record remained open until August 30, 1991, to allow interested persons 
to submit supplementary statements and data.
    During the rulemaking process, MSHA received written and oral 
comments from all segments of the mining community. The Agency's final 
rule addresses the comments received and is consistent with the goals 
of the Federal Mine Safety and Health Act of 1977 (Mine Act), Executive 
Order 12866, the Regulatory Flexibility Act, and the Paperwork 
Reduction Act.
    After analyzing the comments received, the public hearing 
testimony, and technical and health data, the Agency is issuing this 
final rule on abrasive blasting and drill dust control to address 
immediate health concerns. The final rule makes no substantive changes 
to existing regulations for drill dust control at metal and nonmetal 
mines and at underground coal mines. However, the final rule 
establishes new requirements for drill dust control at surface coal 
mines. The final rule also expands existing requirements for abrasive 
blasting at metal and nonmetal mines and establishes new requirements 
for both surface and underground coal mines. The existing respirable 
coal mine dust standards in parts 70, 71, and 90 are unaffected by this 
final rule.
    This final rule is consistent with section 101(a)(6)(A) of the Mine 
Act, which mandates the development of standards dealing with toxic 
substances to attain the highest degree of protection possible for 
miners. Section 101(a)(6)(A) also requires MSHA to take into 
consideration the latest available scientific data in the field, the 
feasibility of the standards, and experience gained under the Mine Act 
and other health and safety laws.
    This rulemaking codifies health standards for abrasive blasting and 
drill dust control in a new part 58 for metal and nonmetal mines and a 
new part 72 for coal mines. In the following discussion, the 
designation ``58/72'' indicates that a standard appears in both parts 
58 and 72.
    In an effort to fully explore the issues presented by this 
rulemaking, MSHA has included in the rulemaking record several 
scientific studies concerning abrasive blasting and drill dust control 
that were published after the close of the comment period on August 30, 
1991. These references are CDC/NIOSH Alert * * * Lead Poisoning in 
Construction Workers, April 1992; CDC/NIOSH Alert * * * Silicosis and 
Deaths in Rock Drillers, August 1992; CDC/NIOSH Alert * * * Silicosis 
and Deaths From Sandblasting, August 1992; Goodman et al., 1992; and 
Mickelsen and Froehlich, May 1993. None of these references are 
entirely new data, but rather they further confirm the Agency's 
rulemaking decision and address concerns raised by commenters. MSHA 
reviewed these documents in order to attain its statutory obligation to 
consider the latest available scientific data in the field.

II. General Introduction

    Whenever miners conduct abrasive blasting or drilling they are 
exposed to serious health hazards that require implementation of 
specific dust controls before engaging in the activity. Enforcement by 
using the permissible exposure limits alone would provide inadequate 
protection for miners in these activities. During abrasive blasting and 
drilling, there is the potential for extremely high exposures in short 
periods of time to both the miners doing the abrasive blasting or 
drilling and to other miners in the immediate area. Relying on samples 
could allow miners to receive extremely hazardous doses of contaminants 
before sampling results could be analyzed. In addition, miners could 
face rapidly changing environments, all having potential for high 
exposure. In addition, during abrasive blasting, although the type of 
abrasive material may remain constant, the coatings of the base 
material and the accumulated contaminants in the recycled abrasive 
material may cause exposure to vary widely (Rekus, 1988; Mickelsen and 
Froehlich, 1993).
    Administrative controls, which control exposures by limiting the 
amount of time a miner is in a contaminated atmosphere, are not 
appropriate for abrasive blasting and drilling operations. Inherent in 
the effective use of administrative controls is the assumption that the 
environmental exposure will remain constant or predictable. This is not 
characteristic of these two operations.
    Due to the nature of the work being performed, the location of 
these activities can change rapidly. The frequent change of location 
also can make it extremely difficult to get sampling results quickly 
enough to effectively evaluate a miner's current exposure. This is 
particularly true in the case of independent contractors who, by the 
time sampling results are evaluated, may have moved to another location 
or mine. There also exists the problem of maintaining sample integrity 
during abrasive blasting operations. When sampling is done outside of 
an abrasive blasting hood, high velocity rebounding or ricocheting 
abrasive material from the blasted surface can destroy the sample.
    Because of these factors, the final rule specifies engineering 
controls for drill dust control at all mines and requires a totally 
enclosed system or an abrasive blasting respirator during abrasive 
blasting operations.
    Exposure to silica is a significant health hazard in abrasive 
blasting and in drilling. When workers inhale silica, the lungs react 
by developing fibrotic nodules and scarring around the trapped silica 
particles. This condition is known as silicosis and can result in 
respiratory difficulty and eventually death. Symptoms associated with 
silicosis include shortness of breath, fever, and cyanosis. Severe 
fungal or mycobacterial infections, such as tuberculosis, often cause 
complications and may be fatal. Dust-impaired macrophages can no longer 
function effectively in fighting disease by killing mycobacteria and 
other organisms.
    It is generally believed that the silica dust overwhelms 
macrophages in the lungs (Craighead et al., 1988). This can be due to 
silica toxicity or to a combination of toxicity and dust overload 
(Morrow, 1988; Claypool, 1988; Berkow, 1987). When a person is exposed 
to respirable dust containing crystalline silica, three types of 
silicosis may occur, depending on the dust concentration. Chronic 
silicosis usually occurs following relatively low exposures over 10 or 
more years. Accelerated silicosis results from exposure to high 
concentrations over 5 to 10 years. Acute silicosis or silico-
proteinosis occurs from exposure to the highest concentrations, with 
symptoms developing within a few weeks to 4 or 5 years from initial 
exposure (Merchant, 1986). Acute silicosis is characterized by the 
accumulation of an amorphous granular lipoprotein released into the air 
spaces and rapid development of respiratory disability in a few years 
(Vallyathan, 1988). Silico-proteinosis results from dust overload as 
well as silica toxicity (Claypool, 1988; Morrow, 1988; Heppleston et 
al., 1970; Rubin et al., 1980).
    When particles impact a surface during abrasive blasting, they 
typically fracture into finer particles and become airborne. Inhalation 
of freshly fractured silica particles appears to produce a more severe 
lung reaction. Vallyathan (1988) studied freshly fractured silica dust 
and found it exhibited more toxic characteristics than silica that had 
aged at least 30 hours. Freshly fractured silica can react with water 
to release short-lived oxygenated free radicals. Alveolar macrophages 
are stimulated to a greater extent by freshly fractured free silica 
than silica that has been aged. Vallyathan theorizes that this freshly 
fractured silica and macrophage interaction may contribute to 
development of acute silicosis, which is associated with sandblasting, 
rock drilling, tunnelling, and silica flour mill operations.

III. Abrasive Blasting

A. Introduction

    Abrasive blasting is the technique of projecting particles to 
remove paint or other unwanted substances from a surface for the 
purpose of preparing it for painting, welding, or other activities. In 
mining, the location and type of equipment being cleaned by abrasive 
blasting may change during every operation. The abrasive material can 
be composed of a single substance, such as silica, or a composite 
material, such as slag. The abrasive material, as well as anything 
removed from the object or surface, can become airborne. In some 
instances, the abrasive material can be collected and reused. This 
process has the potential for accumulation of various toxic substances, 
such as lead from paint (Rekus, 1988; CDC/NIOSH Alert, April 1992; 
Mickelsen and Froehlich, 1993). The exposure hazard associated with 
abrasive blasting is dependent on the type of abrasive blasting 
conducted, the type of abrasive material used, and the substance being 
abraded. Abrasive blasting represents a unique situation in mining that 
is difficult to control by using traditional means.
    There are several different methods of abrasive blasting. Air 
pressure blasting is the most commonly used technique in mining. In 
this process, air pressure is used to propel abrasive material at a 
high velocity against an object to abrade unwanted substances from its 
surface. This type of abrasive blasting has the greatest potential to 
cause overexposure to toxic substances resulting from the abrasive 
material itself or the substances removed.
    Another abrasive blasting method uses abrasive material entrained 
in water or other liquid media. The abrasive material is propelled by 
either liquid pressure or a combination of liquid and air pressure. The 
abrasive material entrained in the liquid media is forced to strike an 
object at a high velocity, which causes unwanted substances to be 
abraded. Though the potential for overexposure is reduced by the water 
used in this method, a health hazard still exists due to small 
fractured particles found in the mist that is generated. After 
blasting, cleanup of dried materials also can be a potential exposure 
problem (Craighead et al., 1988).
    In mining, abrasive blasting is a commonly used method of cleaning 
surfaces in preparation for painting or welding. It is generally done 
on a periodic basis, most commonly during maintenance procedures and 
plant overhaul. For these activities, the hazards of abrasive blasting 
in mining are the same as those in general industry. The references 
cited in this preamble generally relate to studies conducted on non-
miners. Documentation of similar disease prevalence in miners 
performing abrasive blasting is limited because miners who perform 
abrasive blasting are grouped into maintenance or general laborer job 
categories and, thus, are often difficult to identify. Also, many mine 
operators employ independent contractors to perform these activities, 
and disease prevalence among such contractors is difficult to track. 
Because the process and materials are essentially the same in mining as 
in general industry, MSHA believes that miners performing abrasive 
blasting experience risks similar to those described in the scientific 
studies cited in this preamble that address industries other than 
mining.

B. Background

1. Metal and Nonmetal Mining
    Existing metal and nonmetal standards at 30 CFR 56/57.5010 prohibit 
the use of silica sand or other materials containing more than 1 
percent free silica as an abrasive material in abrasive blasting at all 
surface mines and at the surface areas of underground mines, unless all 
exposed persons are protected by a full-flow respirator or equivalent. 
Existing Sec. 57.5016 prohibits the use of silica sand or other 
materials containing more than 1 percent free silica as an abrasive 
substance in abrasive blasting operations underground.
    The majority of abrasive blasting performed at metal and nonmetal 
mines is conducted on the surface and most of these operations are 
carried out by hand-held dry blasting methods. In almost all of these 
operations, abrasive blasting hoods with supplied air are used to 
protect the worker. These hoods are approved by the National Institute 
for Occupational Safety and Health (NIOSH). Also, small abrasive 
blasting work boxes are used in some maintenance shops.
2. Coal Mining
    Currently, MSHA does not specifically regulate abrasive blasting at 
surface and underground coal mines. However, 30 CFR 75.1720 and 77.1710 
require protective clothing for protection against the impact of 
particles from such operations at coal mines. Abrasive blasting occurs 
at a small number of surface and underground coal mines and then only 
on an infrequent basis. These operations may be performed by either the 
mine operator or an independent contractor. MSHA has observed abrasive 
blasting at coal mines where adequate respiratory protection was not 
being worn. Due to the serious health risk of overexposure to 
crystalline silica and other materials being used, the final rule 
requires the use of engineering controls or personal protective 
equipment at all abrasive blasting operations.

C. Abrasive Blasting--Toxicity

    For many years, abrasive blasters have been considered to be at 
high risk of developing silicosis (Craighead et al., 1988). The use of 
sandblasting for the purpose of cleaning metal surfaces before painting 
has been prohibited by law in the United Kingdom since 1949 and in the 
European Economic Community since 1966 (Ziskind, 1976). The increased 
use of sand as an abrasive in the United States since World War II was 
noted to have produced a resurgence of accelerated silicosis in 
sandblasters (Ziskind, 1976). In 1974, NIOSH recommended that silica 
(or other substances containing more than 1 percent free silica) be 
prohibited as an abrasive blasting material (NIOSH, 1974).
    Early reports of acute silicosis among sandblasters include 
Buechner and Ansari (1969), who reported evidence of an alveolar 
proteinosis-like response of pulmonary tissue to occupational silica 
exposure. Autopsy examination of four sandblasters revealed silica 
crystals and a protein material in the lungs. The workers had 
sandblasted for an average period of 4 years.
    Abrasive blasters are also at high risk of developing active 
tuberculosis (Bailey et al., 1974). Merewether (1936) found that the 
average duration of employment at the time of death was 8.3 years for 
abrasive blasters with silico-tuberculosis, compared to 32 years for 
this fatal combination in other occupations. Bailey et al. (1974) also 
found similar results. Merewether (1936) reported that 5.4 percent (24 
of 441) of the sandblasters in his study in Great Britain died from 
silicosis or silicosis with tuberculosis in a 3.5-year period.
    In 1988, a physician reported three cases of silicosis in 
sandblasters (CDC MMWR, 1990). One of these individuals, a 34-year-old 
man, died with acute silicotic alveolar proteinosis. Later 
investigations revealed an additional seven sandblasters who had 
silicosis. All worked at one facility that used a mixture of flint and 
garnet to sandblast oil pipe. The mean duration of exposure was 4.5 
years, with one case as short as 18 months. Blast cabinets and 
protective booths were poorly designed and not maintained. Workers wore 
only disposable respirators and none had been fit tested.
    In another case, a 49-year-old nonsmoker with a 6-year history as a 
sandblaster was admitted to a hospital complaining of difficulty in 
breathing, cough, lack of appetite, fever and a 20-lb weight loss 
(Owens et al., 1988). He was diagnosed with chronic silicosis and 
bacterial pneumonia and died on the twentieth day of his hospital stay.
    Four sandblasters in a tombstone factory developed acute silicosis 
after an average of 3-years' exposure at ages 23, 37, 38, and 47 
(Suratt et al., 1977). Three of the four are known to have died from 
silicosis. It was determined that the blasting agent used during 
sandblasting contained 98 percent crystalline free silica. The 
employees worked inside enclosed but vented blasting chambers and wore 
negative pressure half-mask respirators with disposable filters.
    Bailey et al. (1974) examined the records of 88 sandblaster-
painters who were admitted to Charity Hospital in New Orleans. Of 
these, 83 had silicosis and 22 were confirmed as having tuberculosis. 
The mean age of these 22 individuals was 44, with an average exposure 
of 10 years. At the time of the study, 27 percent (8 of 22) had died. 
Three of these individuals died of ``acute'' silicosis, which had 
characteristics of pulmonary alveolar proteinosis. The average age at 
the time of death was 44.2 years, with an average exposure of 8.3 
years. The authors note that in almost all of the 22 cases, the 
sandblaster hoods were not attached to an external air supply.
    Samimi et al. (1974) studied sandblasting and associated workers on 
steel fabrication yards. They sampled sandblasters and workers 
physically located near the abrasive blasting operations. Personal 
exposure of helpers, pot handlers, painters, and welders indicated an 
average exposure from 1.9 to 7.4 times the permissible threshold limit 
value (TLV), with the helper having the highest exposure among the 
secondary occupations. Environmental samples on the outside of abrasive 
blasting hoods were as high as 37.25 mg/m\3\, which was 318 times the 
TLV. Samples taken inside non-supplied-air abrasive blasting hoods 
exceeded the TLV in all cases, with the highest exposure being 80 times 
the TLV. Although sampling data indicated that overexposures occurred 
with supplied-air respirators being used, the authors noted that this 
may have been due to sampling during times when the respirator was not 
continually worn, as well as to poorly maintained equipment. Samples 
taken under modern and well-maintained hoods indicate exposures would 
be only one-third of the TLV.
    In studies, other abrasives used instead of silica also have been 
demonstrated to be fibrogenic. MacKay et al. (1980) found that 
commercial coal-slag derived grit produced pulmonary fibrosis in rats. 
The copper slag tested did not produce fibrosis, but did produce 
granulomas.
    Stettler et al. (1988) studied the fibrogenic and carcinogenic 
potential of copper and nickel smelter slags that have been used as a 
substitute for sand in abrasive blasting. The copper slags not only 
produced some fibrosis, but also produced lung tumors in the rats. The 
authors were unable to determine the exact causative agent because many 
trace elements, such as arsenic and beryllium, were present in the 
slags.

D. Control Technology

    Abrasive blasting creates high particulate concentrations within 
open or enclosed spaces where the work is performed. The force of the 
abrasive stream (60 to 120 pounds per square inch (psi)) produces fine 
fragments of respirable size (less than 10 micrometers (m) in 
diameter). A high percentage of the particles are in the 1 to 3 
m range in which alveolar deposition is significant (Bailey et 
al., 1974).
    MSHA recognizes that there are limitations in the engineering 
controls for abrasive blasting in mining. Abrasive blasting, by its 
nature, is used to prepare equipment for maintenance. Because the 
equipment to be prepared can vary considerably in size and location at 
the mine, it would be extremely costly and technically very difficult 
to build temporary enclosures around the equipment with properly 
designed ventilation and dust filtration equipment to prevent exposure 
to miners. Some small equipment can be easily moved, which allows for 
abrasive blasting of that equipment to be performed in commercially 
available boxes, cabinets, or blasting rooms. Blast cleaning cabinets 
are used to clean relatively small objects that can be manipulated by 
hand. When using blasting cabinets, the operator stands outside of the 
enclosed cabinet and uses a set of attached gloves or remote controls 
to perform the blasting operation inside the enclosure. The blasting 
media is maintained inside the enclosed cabinet by negative pressure. 
When operators use a properly designed and maintained blasting cabinet, 
exposure to hazardous material is minimal.
    The majority of abrasive blasting in mining is done on large 
equipment at varied locations on the mine site. In these cases, the 
primary means of controlling exposure is the NIOSH-approved abrasive 
blasting hood. This hood has the advantage of providing safety 
protection from the impact of projected particles, as well as 
respiratory protection from toxic materials.

E. Summary and Explanation of Rule

    Paragraph (a) of Secs. 58/72.610 is derived from existing Secs. 56/
57.5010 for metal and nonmetal mines. Sections 56/57.5010 prohibit the 
use of materials containing more than 1 percent free silica as an 
abrasive substance in abrasive blasting operations at surface areas of 
metal and nonmetal mines, unless all exposed persons are protected with 
full-flow respirators or equivalent. Under the final rule, when an 
abrasive blasting operation is performed, all exposed miners must 
properly use respirators approved for abrasive blasting by NIOSH or the 
operation must be done in a totally enclosed device.
    A commenter to the proposed rule recommended that MSHA require 
supplied-air respirators at surface mines, unless the work being 
performed was in a totally enclosed device with the operator outside 
the device. This commenter stated that eliminating silica-containing 
materials from abrasive blasting will not necessarily eliminate the 
associated health hazards, because animal experiments with other 
abrasive substitutes have produced fibrosis or scarring of the lungs. 
In addition, NIOSH recommended that abrasive blasting respirators be 
used whenever there is detectable silica in the abrasive blasting 
material, even when it constitutes less than 1 percent.
    MSHA agrees with the commenter that other abrasive materials can 
present a health hazard in abrasive blasting. The final rule, 
therefore, expands the scope of the proposed rule to address these 
hazards by requiring respirators approved for abrasive blasting to be 
used when abrasive blasting is conducted, unless the work is performed 
in a totally enclosed device with the operator outside the device. 
Abrasive blasting respirators will also provide the necessary safety 
protection because they are designed to protect the wearer's head and 
neck against impact and abrasion from rebounding material, as well as 
provide respiratory protection. The impact of high-velocity rebounding 
or ricocheting abrasive material from the blasted surface can penetrate 
other types of personal protective equipment.
    Existing metal and nonmetal Secs. 56/57.5010 require the use of 
``full-flow respiratory protection or equivalent'' when using abrasives 
containing more than 1 percent free silica. ``Full-flow'' is an 
outdated term referring to a respirator that had a flow of air 
mechanically forced into the facepiece, as opposed to a negative-
pressure respirator that requires inhalation by the wearer to bring air 
through the filter into the facepiece. A ``full-flow'' respirator does 
not easily correspond to current NIOSH certification of respiratory 
protection. The proposed rule replaced ``full-flow respiratory 
protection or equivalent'' with ``supplied-air respirator approved for 
abrasive blasting'' which required NIOSH approval for that use.
    Since the publication of the proposed rule, powered air-purifying 
respirators have received NIOSH approval for use in abrasive blasting 
operations. Powered air-purifying respirators approved by NIOSH for 
abrasive blasting would meet the current standard of ``full-flow 
respiratory protection or equivalent.'' Therefore, MSHA is deleting the 
words ``supplied-air'' in the final rule to permit the use of any 
respirator approved by NIOSH for abrasive blasting. This will not 
result in any diminution of safety for the miner, but will permit the 
use of any new respiratory protection that has been approved by NIOSH 
for abrasive blasting operations.
    NIOSH recommended banning the use of any product containing more 
than 1 percent free silica as an abrasive substance at all mines. They 
also recommended banning the use underground of any product that 
contained any detectable silica, including those containing less than 1 
percent. NIOSH suggested that at surface operations where abrasive 
blasting products containing any detectable silica up to 1 percent are 
used, MSHA should require the use of abrasive blasting respirators.
    In the preamble to the proposed rule, MSHA used the terms 
``quartz'' and ``free silica'' interchangeably in the discussion on 
abrasive blasting, although the term ``1 percent quartz'' was used in 
the proposed rule itself. NIOSH in its comments expressed concern about 
the proposed exemption of material containing ``1 percent free silica 
or less.'' In the final rule, MSHA is using ``1 percent free silica'' 
which is consistent with the wording of the current metal and nonmetal 
standard and is the term used by NIOSH.
    MSHA disagrees with the suggestion that substances containing more 
than 1 percent free silica be banned at surface locations. Adequate 
protection will be provided to miners with the requirement that miners 
exposed to abrasive blasting use respirators approved for abrasive 
blasting or the operation be conducted in totally enclosed devices. 
Several types of abrasive blasting enclosures are commercially 
available and can be used successfully to control exposure to all 
contaminants, not just silica. Alternatively, abrasive blasting 
respirators also offer protection against all contaminants, including 
silica. As a result, the final rule does not ban the use of abrasive 
blasting materials containing silica at surface operations.
    One commenter recommended monitoring of the environment when 
abrasive blasting products containing less than 1 percent free silica 
are used. This commenter suggested that abrasive blasting respirators 
or engineering controls be required if the level of exposure to 
respirable quartz dust at surface operations exceeds 50 g/
m\3\. The requirement in the final rule requiring enclosure or abrasive 
blasting respirators affords more protection to the miners.
    Other commenters recommended that the proposed section on abrasive 
blasting be deleted and that an exposure limit for silica sand govern 
the exposure during abrasive blasting operations. Because of factors 
previously discussed, specifying controls is necessary. Generally, it 
is not practical to conduct monitoring in an abrasive blasting zone 
because the sampling device could be destroyed or damaged by rebounding 
material. In addition, because of the wide variability in blasting 
operations, sampling is often inadequate as a means of assessing the 
miners' exposures. The safety hazard associated with abrasive blasting 
is such that hoods or enclosures are necessary to ensure better 
protection for miners engaged in abrasive blasting activities.
    Paragraph (b) of Secs. 58/72.610 is derived from existing metal and 
nonmetal Sec. 57.5016 and prohibits the use of silica sand or other 
materials containing more than 1 percent free silica as an abrasive 
substance in abrasive blasting at underground mines. Currently, MSHA 
does not explicitly regulate abrasive blasting underground at coal 
mines. However, Sec. 75.1720 requires protective clothing for 
protection against the impact of particles from such operations. NIOSH 
and the majority of commenters recommended that abrasive blasting 
materials containing more than 1 percent free silica be banned 
underground. MSHA agrees because airborne respirable silica could be 
carried from an abrasive blasting operation throughout the mine by the 
ventilation system, thus exposing unprotected miners. In addition, 
there are substitute abrasives that have been used effectively for this 
type of work underground. Accordingly, the Agency has retained the 
provision from the proposed rule which would ban the use underground of 
abrasive blasting materials containing more than 1 percent free silica.
    Because Secs. 58/72.500, respiratory protection, of the proposed 
Air Quality standard have not been promulgated, MSHA uses the term 
``properly used'' and ``approved by NIOSH'' in Sec. 72.610(a) to assure 
protection. Section 58.610 refers to Secs. 56/57.5005 to assure 
continued proper use of respiratory protection. When the respiratory 
protection provisions of the Air Quality rulemaking are promulgated, 
Secs. 58/72.610 will be modified to refer to that section.

IV. Drill Dust Control

A. Introduction

    Drilling operations have long been recognized as causing 
respiratory hazards in mining. Most rock drilling produces respirable, 
silica-bearing dust that can cause silicosis and alveolar proteinosis. 
All types of silicosis have been documented in drillers. In 1958, the 
Public Health Service, in conjunction with the Bureau of Mines, issued 
a report on silicosis in metal and nonmetal mining that identified 
drilling as one of the most prolific dust-producing operations. In 
August 1992, the CDC/NIOSH of the Public Health Service again 
reemphasized its earlier warnings on silicosis occurring in rock 
drillers. In this Alert, NIOSH described 23 cases of silicosis 
occurring in rock drillers, including 11 rock drillers in coal mines. 
MSHA believes that control of drill dust also will prevent the 
development of pulmonary alveolar proteinosis, as well as a mixed dust 
fibrosis and silico-proteinosis.
    MSHA has recognized the health hazard presented by drilling in 
underground coal mining and that surface coal mines also need the 
additional protection set forth in this final rule. In metal and 
nonmetal mines under existing regulations over the past 13 years, MSHA 
had three reports of pneumoconiosis in rock drillers and two cases in 
driller helpers. Over the past 10 years, there were 30 cases of 
pneumoconiosis reported to MSHA in highwall drill operators and helpers 
at surface coal mines.
    In addition, Banks (1983) identified three cases of acute silicosis 
in coal miners. Parker et al. (1989) identified nine cases of silicosis 
in surface miners in a 10-year period in West Virginia. The median age 
of the miners was 35 years. All were drillers, driller helpers, or 
supervisors with a median of 6 years above-ground exposure. Four were 
nonsmokers. Two had acute silicosis, one of whom died within 2 years of 
diagnosis. Five had accelerated silicosis, one of whom had silico-
tuberculosis. Two with longer periods of exposure were diagnosed as 
having chronic silicosis. Parker concluded that there were a number of 
inadequately protected individuals among above-ground workers.
    All drillers and other miners must be protected from the inhalation 
hazard of respirable drill dust. In the history of rock drilling, 
various control techniques have been developed to reduce the amount of 
dust emitted from the drill. Installing drill dust controls at the 
source can reduce the amount of dust emitted and is effective in 
protecting all miners at a mine. Many of these source-control 
techniques are readily available and effective in the prevention of 
pneumoconiosis.

B. Background

1. Metal and Nonmetal Mining
    The Public Health Service has reported that drilling was one of the 
most prolific dust-producing operations to which miners were exposed 
(Silicosis in the Metal Mining Industry, 1963). In that study, 11 
percent of the samples collected for drilling operations contained 
excessive concentrations of silica-bearing dust. The study also cited 
improper ventilation, dry collaring of holes, and defective equipment 
as the primary causes of overexposure. In Medicine in the Mining 
Industries (1972), wet drilling was recognized as an efficient means of 
dust control.
    Existing Secs. 56/57.5003 for metal and nonmetal mines require that 
drill holes be collared and drilled wet or that other efficient dust 
control measures be used when drilling non-water-soluble materials. 
Efficient dust control measures also are required when drilling water-
soluble materials. MSHA issues a citation when a drill dust control is 
missing, defective, or obviously ineffective by sight. In those cases 
where it is not obvious that a control is ineffective, an MSHA 
inspector has the option of reviewing the manufacturer's specifications 
or other pertinent data, or sampling to determine its effectiveness. 
Currently, MSHA issues about 90 citations and 3 orders per year for 
violations of Secs. 56/57.5003.
2. Coal Mining
    The development of silicosis and pneumoconiosis among underground 
coal miners has been well documented, particularly among roof bolters 
and transportation workers. Existing Secs. 70.400 through 70.400-3 
address drill dust controls at underground coal mines. MSHA issues a 
citation for a violation of Sec. 70.400 if visual observation indicates 
that the drill dust controls on the equipment are not functioning 
properly. Currently, MSHA issues about 15 such citations per year. 
Section 72.630 of the final rule is comparable to existing Secs. 70.400 
through 70.400-3 and MSHA's current interpretation of the regulation. 
Likewise, Sec. 72.630 is a work practice standard that does not require 
sampling.
    Surface coal miners were not recognized as facing as serious a risk 
as underground coal miners for many years (Parker et al., 1989). 
Evidence has indicated that highwall drill operators and helpers at 
surface coal mines have an increased risk of pneumoconiosis. Re-
analysis by Banks et al. (1983) of data from a previous U.S. Public 
Health Service survey of surface coal miners, after exclusion of miners 
with underground mining experience, showed that 38 percent of the cases 
of pneumoconiosis in surface coal miners occurred in drill-crew members 
even though this group comprised only 11 percent of the study 
population.
    In a 1984 evaluation of the prevalence of pneumoconiosis in surface 
coal mine drillers, Amandus et al. found a significantly higher 
incidence of category 1 or higher pneumoconiosis in persons with more 
than 10 years surface drilling experience than in those with less than 
10 years or no drilling experience. Results of this study also 
indicated that the average coal mine dust level was significantly 
higher among drillers than that found for all miners.
    Later Piacitelli et al. (1990) reported that the respirable coal 
mine dust samples submitted by coal mine operators and MSHA inspectors 
from 1982 to 1986 were usually well below the 2.0 mg/m3 allowable 
limit for all surface job categories. However, samples collected for 
highwall drillers and helpers indicated that 78 percent and 77 percent, 
respectively, exceeded the quartz exposure limit and that 10 to 15 
percent of miners in both categories exceeded the 2.0 mg/m3 
respirable coal mine dust standard.
    Between 1989 and 1993, MSHA issued 112 citations for exceeding the 
allowable limit for respirable dust on highwall drill operators and 
helpers, of which 62 were for exceeding the 2.0 mg/m3 respirable 
dust standard. The remaining 50 citations were issued for exceeding the 
reduced respirable dust standard due to quartz content. As of July 
1993, MSHA had placed 79 active highwall drills on a reduced respirable 
dust standard due to the quartz concentration in respirable dust 
samples collected on the drill operators. Also, there are 410 active 
roof bolters in underground coal mines on a reduced respirable dust 
standard due to quartz concentration on collected respirable dust 
samples.
    Notwithstanding Agency enforcement efforts, cases of silicosis 
continue to be reported among surface coal miners. Therefore, in 1989, 
MSHA proposed that drillers be protected at surface operations and that 
the requirements be clarified for underground drillers. The final rule 
is a work practice standard that does not require sampling. This 
standard, in conjunction with existing regulations, is intended to 
provide miners with more protection from exposures to harmful amounts 
of silica and respirable coal mine dust.

C. Drill Dust--Toxicity

    Pneumoconiosis began to receive increased attention toward the end 
of the last century as a result of the introduction of machine drills 
and the large quantities of dust they generate. Silicosis has long been 
recognized as a health risk in rock drillers (Silicosis in the Metal 
Mining Industry, 1963). In the past, rock drillers in underground coal 
mines were known to have developed silicosis, but drillers at surface 
coal mines were not considered to be at significant risk (Fairman et 
al., 1977). However, more recent studies indicate that surface rock 
drillers are being diagnosed with silicosis as well as other 
pneumoconioses (Banks et al., 1983; Parker et al., 1989; Goodman et 
al., 1992; Amandus et al., 1984; Piacitelli et al., 1990). A study 
conducted by NIOSH in 1987 of silica dust exposure to drill crews 
drilling overburden on a highwall at a surface coal mine indicated the 
occurrence of significant overexposures and a prevalence of 
pneumoconiosis five times greater than other surface workers (NIOSH 
MHETA 87-173-1882).
    The August 1992 CDC/NIOSH Alert on Rock Drillers referenced a 
number of cases of silicosis among miners. One case involved an 
individual who first experienced respiratory symptoms in 1986 at age 33 
(Goodman et al., 1992). The subject was a quarry driller using wet 
methods to suppress drill dust from 1973 to 1983. After 1983, he worked 
primarily as a driller at a surface coal mine using no controls. The 
miner died in 1991 of progressive respiratory failure.
    Another driller reported respiratory problems in 1979 at age 34 
(Banks et al., 1983). His history indicated that for the previous 5 
years he had operated a rotary drill at a surface coal mine using dry 
drilling methods. This miner died of respiratory failure in 1981. A 
medical survey of nine other drillers working for the same company 
found two additional miners, ages 28 and 31, with accelerated silicosis 
after fewer than 6 years exposure.
    One hospital in West Virginia reported seven cases of silicosis in 
surface miners from 1978 to 1988. The cases involved miners with a 
median age of 35 working in surface drilling for an average of 6 years 
(Parker et al., 1989). One case had active tuberculosis. In addition, a 
second possible case of tuberculosis was identified.
    Ezenwa (1982) studied environmental and host factors in mines and 
mills. In Quebec metal mines, Ezenwa found that a significantly larger 
portion of miners who worked in drilling and crushing (associated with 
high dust levels) developed silicosis in 15 years relative to other 
occupations over the same time period. Of the 35 men with accelerated 
silicosis, 37 percent had working experience as drillers.

D. Drill Dust Control--Technology

    Various effective drill dust control techniques have been developed 
that control the dust at the source. Many of these techniques are 
readily available and effective in the prevention of respirable drill 
dust overexposures. In addition, these dust control techniques can 
reduce the hazard from drill dust for other miners in the mine as 
opposed to personal respiratory protection equipment that only protects 
the individual wearing it, and then only if worn properly.
    Most failures of drill dust controls are readily identified and 
easily corrected. Rather than mechanical breakdown of the controls, 
malfunctions are generally the result of oversights or poor 
maintenance, such as failure to turn on water, to fill water-holding 
tanks, or to empty filters.
    The general types of dust controls for rock drilling are wet 
methods, dry methods, and ventilation control in underground coal 
mines. Wet drilling methods are known to be effective for dust control 
with non-water-soluble materials. These methods have been used as early 
as 1922 and are inexpensive, practical, reliable, and effective in 
controlling drill dust (Silicosis in the Metal Mining Industry, 1963). 
Examples of wet drilling controls include the introduction of water 
through a hollow drill stem, flooding of drill-holes, and water sprays. 
Dry methods include various methods to capture the dust at the source 
(the drill-hole), usually by vacuum, with subsequent removal of the 
dust from the work area air by filtration or other means. Effective dry 
dust collectors are readily available from several equipment 
manufacturers for drilling both water-soluble and non-water-soluble 
materials. General ventilation is not usually effective in underground 
coal mines for drill dust control, unless it can rapidly disperse and 
carry away the drill dust as well as direct the dust away from any 
workers in the area.

E. Summary and Explanation of Rule

1. Sections 58/72.620
    Section 58.620 is a recodification with no substantive change of 
existing Secs. 56/57.5003, which addresses drill dust control at metal 
and nonmetal mines. Section 72.620 established new requirements for 
drill dust control at surface coal mines and surface areas of 
underground coal mines. The final rule provides that drill holes be 
collared and drilled wet or that other effective dust control measures 
be used when drilling non-water-soluble material. The final rule also 
requires effective dust control measures when drilling water-soluble 
material.
    NIOSH supported establishing rules for drill dust control at 
surface coal mines because the potential exists for significant 
overexposure to respirable free silica.
    Many commenters objected to the specific control requirements 
contained in proposed Secs. 58/72.620. These commenters recommended 
that MSHA delete all of the existing and proposed drill dust control 
standards and suggested that any new regulations addressing this issue 
be performance oriented. Commenters stated that when judging how to 
reduce miners' exposure to drill dust, operators should be given wide 
discretion and be allowed to take into account differences in mine 
conditions and mining operations.
    Other commenters stated that MSHA should provide the same 
compliance options to metal and nonmetal and surface coal mine 
operators as are currently provided to underground coal mine operators. 
These commenters recommended that the language of proposed Sec. 72.630 
be made applicable to all mines. These commenters stated that by 
requiring wet drilling, MSHA would be suppressing the development of 
new technology and that the Agency was not taking into consideration 
other effective measures of dust control, such as positive pressure 
cabs.
    The final rule allows mine operators the option of using controls 
that are both practical and effective in controlling miners' exposures 
to drill dust. The methods listed in the final rule are basic and 
effective control technologies that are readily available to mine 
operators. In addition, the phrase ``or other effective dust control 
measures'' is included in the final rule to enable mine operators to 
use methods other than those specifically listed in the standard.
    MSHA's primary concern is that any drill dust control method relied 
upon by the operator for the protection of miners' health have a level 
of proven effectiveness. As a result, the proposed language in 
Secs. 58/72.620 is retained in the final rule.
    Likewise, it is MSHA's intent that the final rule allow new 
technology. New methods of drill dust control may be used if their 
effectiveness can be demonstrated. In the same manner, new types of 
drilling may be developed and used if they include controls that are 
effective in controlling drill dust. Metal and nonmetal and surface 
coal mine operators do not have to seek MSHA approval before installing 
``effective'' dust control technology.
    MSHA agrees that positive pressure cabs are effective in 
controlling exposures to dust for persons located within the cabs. 
However, other miners may be working in the area. Because cabs do not 
control drill dust at the source of generation, they are not adequate 
to protect the health of miners located outside the cabs who are 
exposed to the drill dust.
    Many commenters also stated that the proposed standards would be 
redundant and burdensome. They expressed concern that controls would be 
required without regard to actual exposures which mine operators are 
otherwise required to maintain within permissible exposure limits. 
These commenters stated that the presumption that all drill operators 
are overexposed unless there is a dust control system installed on the 
drill is not valid. These commenters recommended that citations for 
drill dust control be issued only when sampling data indicates that a 
miner is overexposed.
    MSHA disagrees with these commenters because the hazard associated 
with drilling operations is so serious and the exposure so variable 
that a permissible exposure limit alone cannot be relied upon as the 
primary means of controlling drill dust exposure. The final rule 
requires that effective drill dust controls be provided, regardless of 
exposure. MSHA's experience has shown that drilling without effective 
dust controls is highly likely to result in overexposure, not only to 
the drill operator but also to other workers in the drilling area. Dust 
generated by drills underground can be carried to other areas of the 
mine by the ventilation system, creating contaminated air throughout 
the mine and exposing unprotected miners. There is evidence that the 
percentage of time that drill operators are overexposed is high enough 
to warrant controls (Banks et al., 1983). In addition, due to the 
nature of the drilling activity, the exposure concentration is not 
always consistent and, in some instances, a miner can be acutely 
exposed before sampling data indicates an overexposure.
    One commenter recommended deleting the second sentence of Secs. 58/
72.620, ``or other effective dust control measures,'' and stated that 
collaring and wet drilling should be the preferred means of drill dust 
control. This commenter stated that a standard requiring only collaring 
and wet drilling would be easier for MSHA to enforce because the 
provision for ``alternative methods'' would require the Agency to 
assess data. This commenter also suggested that operators could file a 
petition for modification with MSHA if they wanted to use an 
alternative dust control method.
    MSHA recognizes that wet drilling is an established practice at 
metal and nonmetal mines. However, there are other methods of drill 
dust control, such as dry dust collectors, which are also effective in 
controlling drill dust. A requirement permitting only wet drilling and 
dry dust collection could stifle new technology that could be effective 
in the control of drill dust. MSHA has had experience enforcing this 
standard at metal and nonmetal mines and will enforce the requirements 
similarly at surface operations of coal mines. In addition, the Mine 
Act does not allow mine operators to petition for modification of 
health standards.
    Some commenters expressed concern that the proposed standards on 
drill dust control would give too much discretion to MSHA inspectors. 
One commenter stated that an inspector could arrive at a mine, observe 
some dust coming from a drill, and issue a citation based solely on his 
subjective conclusion that the dust control method being used was ``not 
effective.'' Some commenters recommended that an inspector be allowed 
to issue a citation only when an operator fails to have drill dust 
controls in place or when sampling results indicate an overexposure.
    Under the final rule, MSHA will cite a mine operator when a dust 
control is missing, defective, or obviously ineffective by visual 
inspection. In those cases where it is not obvious that a control is 
effective, MSHA inspectors would have the option of reviewing 
manufacturer's specifications or other pertinent data relative to the 
design and operation of the dust control or, if practical, collecting 
samples to evaluate its effectiveness.
    One commenter stated that MSHA needed to consider that climatic 
conditions play an important role in ``effective'' dust control. This 
commenter used wet and dry dust-collection systems and, under certain 
conditions, each method could be rendered inoperable. This commenter 
stated that the wet systems fail in cold temperatures, and the dry 
vacuum systems tend to plug when the drill bit enters moist areas. This 
commenter recommended that, as a temporary solution, operators be 
allowed to issue respiratory protection to the affected miners when 
controls fail due to temporary weather conditions.
    MSHA agrees that problems can be encountered by drillers when using 
wet or dry drilling methods. However, there are precautions that the 
operator can take to reduce these problems, such as adding antifreeze 
to the water. Because of the need to control drill dust at the source, 
effective drill dust controls would not include personal protective 
equipment or administrative controls. After reviewing the comments 
received, MSHA has retained the proposed language in the final rule.
2. Section 72.630
    Section 72.630, which addresses drill dust control at underground 
coal mines, recodifies existing Secs. 70.400 through 70.400-3 and 
strengthens the maintenance requirement for dust collectors.
    Paragraph (a) recodifies existing Sec. 70.400 and requires that 
dust resulting from drilling in rock be controlled by use of 
permissible dust collectors, or by water, or water with a wetting 
agent, or by ventilation, or by any other method or device approved by 
the Secretary in the ventilation plan that is as effective in 
controlling the dust. This requirement is not intended to limit the 
introduction of new technology into the mining environment. However, 
because of health and safety concerns at underground coal mines, MSHA 
believes that the Agency should evaluate the effectiveness of new 
technology before it is used.
    Some commenters objected to the specific control requirements 
contained in the standard. Many recommended that MSHA delete all of the 
existing and proposed drill dust control standards and suggested that 
any new regulations addressing this issue be performance oriented. Some 
stated that, when judging how to reduce miners' exposure to drill dust, 
operators should be given wide discretion to take into account 
differences in mine conditions and mining operations.
    A specific standard addressing the health hazards associated with 
drill dust continues to be necessary due to the likelihood of 
overexposure inherent in such operations. Underground coal mine 
operators have the option of using controls which are both practical 
and effective in controlling miners' exposure to drill dust. The 
methods listed in the final rule are basic and effective control 
technologies that are readily available to underground coal mine 
operators. In addition, the phrase ``or by any other method or device 
approved by the Secretary that is as effective in controlling the 
dust'' is included in the final rule in order to enable mine operators 
to use methods other than those specifically listed in the standard. As 
a result, the final rule makes only nonsubstantive editorial changes to 
Secs. 70.400 through 70.400-3 and recodifies them as Sec. 72.630.
    As with Sec. 72.620, many commenters stated that the proposed 
standard would be redundant and burdensome because controls would be 
required with no consideration of actual exposures. These commenters 
stated that the presumption that all drill operators are overexposed 
unless there is a dust control system installed on the drill is not 
valid. These commenters recommended that citations for drill dust 
control be issued only when sampling data indicates that a miner is 
overexposed. As stated above, because the hazard associated with 
drilling operations is so serious and exposure so variable, a 
permissible exposure limit alone cannot be relied upon as the primary 
means of controlling drill dust exposure.
    As stated previously, MSHA will continue to cite a mine operator 
when a dust control is missing, defective, or obviously visually 
ineffective. In those cases where it is not obvious that a control is 
effective, MSHA inspectors will continue to have the option of 
reviewing manufacturer's specifications or other pertinent data 
relative to the design and operation of the dust control, or of 
sampling to determine its effectiveness.
    Paragraph (b) recodifies existing Sec. 70.400-1 which requires 
control of drill dust through the use of permissible dust collectors. 
In addition, as proposed, a new provision clarifies that dust 
collectors must be maintained in permissible and operating condition 
when they are provided as a method of controlling dust. The majority of 
commenters supported MSHA in requiring that dust collectors be 
maintained in permissible and operating condition. NIOSH commented that 
they supported MSHA's proposed rule for drill dust control at 
underground coal mines and that the proposed addition of maintenance 
requirements for dust collectors was appropriate for limiting the 
exposure of miners in these operations to respirable free silica.
    Paragraph (c) recodifies Sec. 70.400-2 with no change in the 
existing requirement that water used to control drill dust be applied 
through a hollow drill steel or stem or by the flooding of vertical 
drill holes in the floor. Some commenters recommended that paragraph 
(c) be deleted because they stated that the provision would place 
limits on the options available to mine operators for the control of 
drill dust at underground coal mines. One commenter stated that the 
wording in the proposed rule would place unnecessary limits on the 
methods by which water could be used to control dust. Another commenter 
stated that the wording in the proposed rule would limit the use of new 
technology and that the requirement to wet drill would be infeasible 
and difficult to implement in areas of low water availability and high 
altitude.
    MSHA does not intend for this standard to be technology stifling. 
As indicated earlier, the operator is not restricted to the methods 
listed in the standard and, if circumstances are such that wet drilling 
is not practical or feasible, the operator has the option of using 
other effective methods approved by the Secretary of Labor. Wet 
drilling can be an inexpensive, practical, and effective means of 
controlling miners' exposure to drill dust at underground coal mines. 
This practice is currently in use at underground coal mines for 
drilling non-water-soluble materials.
    Paragraph (d) recodifies existing Sec. 70.400-3 with no change in 
the existing requirement that air currents be so directed that the dust 
is readily dispersed and carried away from the drill operator or other 
workers in the area. Many commenters stated that this provision was 
unnecessary because a mine operator would be instructed by MSHA not to 
direct the ventilation current toward a drill operator. Other 
commenters stated that the provision that permits the use of 
``ventilation * * * that is effective in controlling the dust'' implies 
that MSHA will have to determine noncompliance through the 
demonstration of an overexposure to a permissible exposure limit. One 
commenter recommended deleting paragraph (d), stating that the 
preferred means of drill dust control should be limited to permissible 
dust collectors, water, or water with a wetting agent. This commenter 
stated that ventilation is less effective in the control of drill dust 
and harder for MSHA to enforce.
    MSHA recognizes that ventilation may not always be a practical 
method of drill dust control and that it is not the predominant method 
used in underground coal mines. Under some circumstances, continuous 
mining machines and roof bolters work on a single split of air, and 
this can result in only the drillers being protected while persons 
working downwind could be exposed. If proper precautions are taken, 
however, ventilation can be an effective method of drill dust control. 
MSHA, therefore, has not deleted paragraph (d). MSHA will continue to 
determine compliance with this requirement under the final rule as it 
has enforced Sec. 70.400-3; i.e., through the measurement of air 
quantity or other measures set forth in a mine's ventilation and 
methane and dust control plan. MSHA does not intend that exposure 
samples be the routine method of determining compliance with this 
paragraph.

V. References

Amandus, H.E. et al., ``A Re-evaluation of Radiological Evidence 
from a Study of U.S. Strip Coal Miners,'' Arch Environ Health 
39(5):346-351, September/October 1984.
Bailey, W.C. et al., ``Silico-Mycobacterial Disease in 
Sandblasters,'' Am Rev Respir Dis 110:115-125, 1974.
Banks, D.E. et al., ``Silicosis in surface coalmine drillers,'' 
Thorax 38:275-278, 1983.
Berkow, R., ed., The Merck Manual of Diagnosis and Therapy (15th 
Edition), 1987. pp. 679-681.
Buechner, H.A. and A. Ansari, ``Acute Silico-Proteinosis,'' Dis 
Chest 55(4):274-284, April 1969.
CDC (Centers for Disease Control), ``Silicosis: Cluster in 
Sandblasters--Texas, and Occupational Surveillance for Silicosis,'' 
MMWR 39(25):433-437, June 1990.
CDC/NIOSH, ``Alert--Preventing Lead Poisoning in Construction 
Workers (Rev. Ed.),'' DHHS (NIOSH) Pub. No. 91-116a, April 1992.
CDC/NIOSH, ``Alert--Preventing Silicosis and Deaths From 
Sandblasting,'' DHHS (NIOSH) Pub. No. 92-102, August 1992.
CDC/NIOSH, ``Alert--Preventing Silicosis and Deaths in Rock 
Drillers,'' DHHS (NIOSH) Pub. No. 92-107, August 1992.
Claypool, W.D., ``Pulmonary Alveolar Proteinosis,'' Ch. 57 in 
Pulmonary Diseases and Disorders (2nd Edition), Vol. 2, by A.P. 
Fishman, 1988. pp. 893-900.
Craighead, J.E. et al., ``Diseases Associated with Exposure to 
Silica and Nonfibrous Silicate Minerals,'' Arch Pathol Lab Med 
112:673-720, July 1988.
Ezenwa, A.O., ``Studies of Environmental and Host Factors 
Influencing Personal Differences in Response to Industrial Silica 
Dust Exposure,'' Ann Occup Hyg 26(1-4):745-752, 1982.
Fairman, R.P. et al., ``Respiratory Status of Surface Coal Miners in 
the United States,'' Arch Environ Health 32(1):211-215, September/
October 1977.
Goodman, G.B. et al., ``Acute Silicosis Responding to Corticosteroid 
Therapy,'' Chest 101:366-370, 1992.
Heppleston, A.G. et al., ``Experimental Alveolar Lipo-Proteinosis 
Following the Inhalation of Silica,'' J Path 101(4):293-307, 1970.
MacKay, G.R. et al., ``Fibrogenic potential of slags used as 
substitutes for sand in abrasive blasting operations,'' AIHAJ 
41:836-842, November 1980.
Merchant, J.A., ed., Occupational Respiratory Diseases, DHHS (NIOSH) 
Pub. No. 86-102, September 1986, pp. 219-241.
Merewether, E.R.A., ``The Risk of Silicosis in Sand-Blasters,'' 
Tubercle 17(25):385-391, June 1936.
Mickelsen, R.L. and P.A. Froehlich, ``Lead-Based Paint Removal Using 
Recyclable Steel Abrasive (Abstract),'' Paper presented at American 
Industrial Hygiene Conference & Exposition '93, New Orleans, LA, May 
15-21, 1993, p. 9.
Morrow, P.E., ``Possible Mechanisms to Explain Dust Overloading of 
the Lungs,'' Fundamental and Applied Toxicology 10:369-384, 1988.
NIOSH, ``Health Hazard Evaluation Report,'' (MHETA 87-173-1882) at 
Jeddo Highland Coal Co., West Pittston, PA, August 1987.
NIOSH, ``Occupational Exposure to Crystalline Silica,'' HEW (NIOSH) 
Pub. No. 75-120, 1974.
Owens, M.W. et al., ``Case Report: Sandblaster's Lung with 
Mycobacterial Infection,'' Am J Med Sci 295(6):554-557, June 1988.
Parker, J.E. et al., ``Surface Coal Mine Drillers and Silicosis: The 
Ten Year West Virginia Experience (Abstract),'' Am Rev Respir Dis 
139:A490, 1989.
Piacitelli, G.M. et al., ``Respirable Dust Exposures in U.S. Surface 
Coal Mines (1982-1986),'' Arch Environ Health 45(4):202-209, July/
August 1990.
Public Health Service and Bureau of Mines, ``Silicosis in the Metal 
Mining Industry,'' Public Health Service Pub. No. 1076, 1963.
Rekus, J.F., ``Working on Structural Steel: The Lead Hazard,'' 
Journal of Protective Coatings & Linings 5(10):38-44, 1988.
Rogan, J.M., ed., Medicine in the Mining Industries, 1972.
Rubin, E. et al., ``Pulmonary Alveolar Proteinosis,'' Radiology 
135:35-41, April 1980.
Samimi, B. et al., ``Respirable Silica Dust Exposure of Sandblasters 
and Associated Workers in Steel Fabrication Yards,'' Arch Environ 
Health 29:61-66, August 1974.
Stettler, L.E. et al., ``Fibrogenicity and Carcinogenic Potential of 
Smelter Slags Used as Abrasive Blasting Substitutes,'' J Toxicol and 
Environ Health 25:35-56, 1988.
Suratt, P.M. et al., ``Case Reports: Acute Silicosis in Tombstone 
Sandblasters,'' Am Rev Respir Dis 115:521-529, 1977.
Vallyathan, V. et al., ``Generation of Free Radicals from Freshly 
Fractured Silica Dust,'' Am Rev Respir Dis 138:1213-1219, 1988.
Ziskind, M. et al., ``State of the Art: Silicosis,'' Am Rev Respir 
Dis 113:643-665, 1976.

VI. Executive Order 12866 and the Regulatory Flexibility Act

    In accordance with Executive Order 12866, MSHA prepared a final 
regulatory impact analysis (RIA) to determine the incremental costs and 
benefits associated with the final rule on drill dust control and 
abrasive blasting. MSHA has determined in its RIA that this rule would 
neither result in major cost increases nor have an effect of $100 
million or more on the economy. The RIA, which is available from MSHA 
upon request, is summarized as follows.

Benefits

    The final rule enhances safety and health, and none of these 
revisions reduce miner protection. In providing an estimate of the 
potential benefits that is based on previous coal miner cases, it needs 
to be noted that some of these miners may have received a majority of 
their exposures in mining activities other than highwall drilling. In 
addition, metal and nonmetal mines, which have had to comply with these 
drill dust controls, perform considerably more highwall drilling than 
do coal mines. Whereas 30 surface coal miner pneumoconiosis cases were 
reported to MSHA during the previous 10 years, only 5 metal and 
nonmetal pneumoconiosis cases were reported to MSHA during this period. 
As a result, MSHA determined that compliance with the new requirements 
for drill dust controls at surface coal mines would have prevented 
between 10 and 20 of the 30 surface coal miner pneumoconiosis cases 
reported to MSHA during the preceding 10 years, for an average of 1 to 
2 cases prevented annually.
    Even though MSHA was unable to identify any specific case that 
would have been prevented by the new abrasive blasting requirements, 
compliance with the final rule will help to prevent potential future 
cases of silicosis and other dust diseases of the lungs.

Costs

    MSHA has compared the costs associated with the existing 
requirements with the costs of the new requirements. Noting that 
approximately 250 coal highwall drillers will require some retrofitting 
at unit costs of about $2,500 for adding a collector or baghouse, about 
$8,000 for installing a dry dust collecting system, and about $7,000 
for installing a wet drilling system, MSHA calculated that compliance 
with the final rule for drill dust controls will cost the coal mining 
industry about $950,000 in first-year costs, which would translate into 
about $155,000 in annualized costs. Annual costs for such items as 
maintenance of dust-collection systems, filter replacement, etc., are 
estimated to be about $95,000. Thus, the total annualized plus annual 
compliance cost is projected to be about $250,000.
    With respect to the abrasive blasting requirements, MSHA determined 
that about 55 metal and nonmetal mines and 20 coal mines would be 
required to purchase new respiratory protective equipment. The unit 
costs for this equipment can range from $900 for a powered, air-
purifying respirator (PAPR); $1,450 for an air-supplied hood 
retrofitted with an existing air compressor; $2,200 for an air-supplied 
hood retrofitted with an air distribution system; and between $1,000 
and $1,500 for an abrasive blasting cabinet.
    MSHA calculated that compliance with the final rule for abrasive 
blasting will cost the metal and nonmetal mining industry about 
$103,000 in first-year costs, which would translate into about $17,000 
in annualized costs. Annual costs for such items as maintenance, filter 
replacement, etc., are estimated to be about $10,000. Thus, the total 
metal and nonmetal annualized plus annual compliance cost is projected 
to be about $27,000.
    For coal mining, MSHA calculated that compliance with the final 
rule for abrasive blasting will cost about $40,000 in first-year costs, 
which would translate into about $7,000 in annualized costs. Annual 
costs for such items as maintenance, filter replacement, etc., will be 
about $4,000. Thus, the total coal annualized plus annual compliance 
cost will be about $11,000.
    MSHA's final rule will have a minimal impact upon labor 
productivity, profits, prices, mining output, and mining employment. 
The Agency foresees no detrimental economic impact to this industry.

Regulatory Flexibility Act

    The Regulatory Flexibility Act requires that agencies evaluate and 
include, wherever possible, compliance alternatives that minimize any 
adverse impact on small businesses when developing regulatory 
standards. This final rule includes alternative compliance methods, 
several of which will directly affect small mining operations.
    MSHA determined that small mines will incur first-year costs of 
about $248,000, or annualized costs of about $41,000. Annual costs for 
small mines will be about $25,000. At the same time, MSHA determined 
that large mines will incur first-year costs of about $846,000, or 
annualized costs of about $138,000. Annual costs for large mines will 
be about $84,000.
    MSHA determined that these new provisions will not generate a 
substantial cost increase for small mines. The lack of a substantial 
cost increase for small mines in conjunction with the fact that similar 
hazards exist in both large and small mining operations indicates that 
regulatory relief is not warranted for small mining operations. 
Therefore, MSHA has determined that the final rule will not have a 
significantly adverse impact upon a substantial number of small 
entities.

VII. Paperwork Reduction Act

    This final rule contains no information paperwork requirements 
subject to the Paperwork Reduction Act of 1980.

Derivation Table

    The following derivation table lists the final rule with the 
existing standard numbers from which it is derived. 

------------------------------------------------------------------------
                  New section                          Old section      
------------------------------------------------------------------------
58.610(a).......................................  56 and 57.5010.       
58.610(b).......................................  57.5016.              
58.620..........................................  56 and 57.5003.       
72.610..........................................  New.                  
72.620..........................................  New.                  
72.630(a).......................................  70.400.               
72.630(b).......................................  70.400-1.             
72.630(c).......................................  70.400-2.             
72.630(d).......................................  70.400-3              
------------------------------------------------------------------------

Redesignation Table

    The following redesignation table lists the existing standard with 
the final rule standard numbers. 

------------------------------------------------------------------------
                     Old section                          New section   
------------------------------------------------------------------------
56 and 57.5003........................................  58.620          
56 and 57.5010........................................  58.610(a)       
57.5016...............................................  58.610(b)       
70.400................................................  72.630(a)       
70.400-1..............................................  72.630(b)       
70.400-2..............................................  72.630(c)       
70.400-3..............................................  72.630(d)       
------------------------------------------------------------------------

List of Subjects in 30 CFR Parts 56, 57, 58, 70, and 72

    Mine safety and health, Surface mining, Underground mining.

    Dated: February 11, 1994.
J. Davitt McAteer,
Assistant Secretary for Mine Safety and Health.

    Accordingly, chapter I of title 30 of the Code of Federal 
Regulations is amended as set forth below:

PART 56--[AMENDED]

    1. The authority citation for part 56 continues to read as follows:

    Authority: 30 U.S.C. 811, 957, and 961.


Sec. 56.5003  [Removed]

    2. Section 56.5003 is removed.


Sec. 56.5010  [Removed]

    3. Section 56.5010 is removed.

PART 57--[AMENDED]

    4. The authority citation for part 57 continues to read as follows:

    Authority: 30 U.S.C. 811, 957, and 961.


Sec. 57.5003  [Removed]

    5. Section 57.5003 is removed.


Sec. 57.5010  [Removed]

    6. Section 57.5010 is removed.


Sec. 57.5016  [Removed]

    7. Section 57.5016 is removed.
    8. A new part 58 is added to subchapter N, 30 CFR chapter I to read 
as follows:

PART 58--HEALTH STANDARDS FOR METAL AND NONMETAL MINES

Subpart A--General

Sec.
58.1  Scope.

Subparts B Through D--[Reserved]

Subpart E--Miscellaneous

58.610  Abrasive blasting.
58.620  Drill dust control.

    Authority: 30 U.S.C. 811, 957, and 961.

Subpart A--General


Sec. 58.1  Scope.

    The health standards in this part apply to all metal and nonmetal 
mines.

Subpart E--Miscellaneous


Sec. 58.610  Abrasive blasting.

    (a) Surface and underground mines. When an abrasive blasting 
operation is performed, all exposed miners shall use in accordance with 
Secs. 56/57.5005 respirators approved for abrasive blasting by NIOSH or 
the operation shall be performed in a totally enclosed device with the 
miner outside the device.
    (b) Underground areas of underground mines. Silica sand or other 
materials containing more than 1 percent free silica shall not be used 
as an abrasive substance in abrasive blasting.


Sec. 58.620  Drill dust control.

    Holes shall be collared and drilled wet, or other effective dust 
control measures shall be used, when drilling non-water-soluble 
material. Effective dust control measures shall be used when drilling 
water-soluble materials.

PART 70--[AMENDED]

    9. The authority citation for part 70 is revised to read as 
follows:

    Authority: 30 U.S.C. 811, 813(h), 957, and 961.


Secs. 70.400, 70.400-1, 70.400-2 and 70.400-3  [Removed].

    10. Sections 70.400, 70.400-1, 70.400-2, and 70.400-3 are removed.
    11. A new part 72 is added to subchapter O to read as follows:

PART 72--HEALTH STANDARDS FOR COAL MINES

Subpart A--General

Sec.
72.1  Scope.

Subparts B Through D--[Reserved]

Subpart E--Miscellaneous

72.610  Abrasive blasting.
72.620  Drill dust control at surface mines and surface areas of 
underground mines.
72.630  Drill dust control at underground areas of underground 
mines.

    Authority: 30 U.S.C. 811, 813(h), 957, and 961.

Subpart A--General


Sec. 72.1  Scope.

    The health standards in this part apply to all coal mines.

Subpart E--Miscellaneous


Sec. 72.610  Abrasive blasting.

    (a) Surface and underground mines. When an abrasive blasting 
operation is performed, all exposed miners shall properly use 
respirators approved for abrasive blasting by NIOSH, or the operation 
shall be performed in a totally enclosed device with the miner outside 
the device.
    (b) Underground areas of underground mines. Silica sand or other 
materials containing more than 1 percent free silica shall not be used 
as an abrasive substance in abrasive blasting.


Sec. 72.620  Drill dust control at surface mines and surface areas of 
underground mines.

    Holes shall be collared and drilled wet, or other effective dust 
control measures shall be used, when drilling non-water-soluble 
material. Effective dust control measures shall be used when drilling 
water-soluble material.


Sec. 72.630  Drill dust control at underground areas of underground 
mines.

    (a) Dust resulting from drilling in rock shall be controlled by use 
of permissible dust collectors, or by water, or water with a wetting 
agent, or by ventilation, or by any other method or device approved by 
the Secretary that is as effective in controlling the dust.
    (b) Dust collectors. Dust collectors shall be maintained in 
permissible and operating condition. Dust collectors approved under 
Part 33--Dust Collectors for Use in Connection with Rock Drilling in 
Coal Mines of this title or under Bureau of Mines Schedule 25B are 
permissible dust collectors for the purpose of this section.
    (c) Water control. Water used to control dust from drilling rock 
shall be applied through a hollow drill steel or stem or by the 
flooding of vertical drill holes in the floor.
    (d) Ventilation control. To adequately control dust from drilling 
rock, the air current shall be so directed that the dust is readily 
dispersed and carried away from the drill operator or any other miners 
in the area.

[FR Doc. 94-3591 Filed 2-17-94; 8:45 am]
BILLING CODE 4510-43-P