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24-065
NIOSH Miner Act Extramural Research for Silica Dust
W.R. Reed
CDC-NIOSH, Pittsburgh, PA USA
G.W. Luxbacher
CDC-NIOSH, Atlanta, GA USA
ABSTRACT
Mine worker exposure to respirable coal dust and silica
dust can result in coal workers’ pneumoconiosis and sili-
cosis which are occupational respiratory diseases that have
no cure and are ultimately fatal. In 2021 the Mine Safety
and Health Administration reported just over 11,000 oper-
ating metal/nonmetal mines with the potential for silica
dust exposure for just under 200,000 miners. The National
Institute for Occupational Safety and Health (NIOSH)
conducts respirable coal and silica dust research associated
with mining through its Office of Mine Safety and Health
Research. NIOSH respirable coal and silica dust research
began under the U.S. Bureau of Mines (USBM), which
initially examined silica dust, progressing to include coal
dust, with a stronger focus after 1969 with the passage of
the Federal Coal Mine Health and Safety Act. A review of
extramural research to develop real-time respirable silica
dust monitor is presented along with a brief history of silica
dust regulation.
INTRODUCTION
Silicosis is an occupational respiratory disease that is caused
by exposures to high levels of respirable crystalline silica
dust. Respirable crystalline silica dust for sampling purposes
consists of dust particles with a D50 of 4.0 µm for total air-
borne particles (the D50 is 4.25 µm based upon the inhal-
able convention) as defined by the International Standards
Organization [1]. The D50 represents the median diameter
of a particle size distribution. The definition of D50, being
50% of particles are less than 4.0 µm and 50% are greater
than 4.0 µm. Silicosis consists of acute silicosis, accelerated
silicosis and chronic silicosis. Acute silicosis develops over
months or over several years through exposures to very high
levels of respirable crystalline silica dust. Chronic silicosis,
most commonly encountered, develops over many years
(to decades) of exposure to respirable crystalline silica dust.
Accelerated silicosis can result from exposure to high levels
with development occurring within 5 to 10 years. Silicosis
is irreversible, has no cure, and is ultimately fatal. In addi-
tion, silicosis can be associated with tuberculosis, lung can-
cer, renal disease, and nonmalignant respiratory diseases
(emphysema, chronic bronchitis, etc.) [2, 3]. The only way
of avoiding silicosis is through prevention of exposure to
respirable crystalline silica dust.
REGULATIONS
The current regulations for respirable crystalline silica dust
in metal/nonmetal mining are listed in Code of Federal
Regulations, Title 30, Chapter I, Subchapter K, Part 56 and
57, Subpart D with the current limits referenced in the
“TLV’s Threshold Limit Values for Chemical Substances
in Workroom Air Adopted by ACGIH for 1973.” As ref-
erenced in this document, for respirable crystalline silica
dust or quartz1, the current limit (as of 2023) is: .For total
dust (respirable and nonrespirable) the limit is .There is
a special category for silicates (1% quartz) where limits
are referenced in the document. If quartz is 1%, then
1. MSHA uses “quartz” for crystalline silica. This convention
will be used throughout the rest of the paper.
24-065
NIOSH Miner Act Extramural Research for Silica Dust
W.R. Reed
CDC-NIOSH, Pittsburgh, PA USA
G.W. Luxbacher
CDC-NIOSH, Atlanta, GA USA
ABSTRACT
Mine worker exposure to respirable coal dust and silica
dust can result in coal workers’ pneumoconiosis and sili-
cosis which are occupational respiratory diseases that have
no cure and are ultimately fatal. In 2021 the Mine Safety
and Health Administration reported just over 11,000 oper-
ating metal/nonmetal mines with the potential for silica
dust exposure for just under 200,000 miners. The National
Institute for Occupational Safety and Health (NIOSH)
conducts respirable coal and silica dust research associated
with mining through its Office of Mine Safety and Health
Research. NIOSH respirable coal and silica dust research
began under the U.S. Bureau of Mines (USBM), which
initially examined silica dust, progressing to include coal
dust, with a stronger focus after 1969 with the passage of
the Federal Coal Mine Health and Safety Act. A review of
extramural research to develop real-time respirable silica
dust monitor is presented along with a brief history of silica
dust regulation.
INTRODUCTION
Silicosis is an occupational respiratory disease that is caused
by exposures to high levels of respirable crystalline silica
dust. Respirable crystalline silica dust for sampling purposes
consists of dust particles with a D50 of 4.0 µm for total air-
borne particles (the D50 is 4.25 µm based upon the inhal-
able convention) as defined by the International Standards
Organization [1]. The D50 represents the median diameter
of a particle size distribution. The definition of D50, being
50% of particles are less than 4.0 µm and 50% are greater
than 4.0 µm. Silicosis consists of acute silicosis, accelerated
silicosis and chronic silicosis. Acute silicosis develops over
months or over several years through exposures to very high
levels of respirable crystalline silica dust. Chronic silicosis,
most commonly encountered, develops over many years
(to decades) of exposure to respirable crystalline silica dust.
Accelerated silicosis can result from exposure to high levels
with development occurring within 5 to 10 years. Silicosis
is irreversible, has no cure, and is ultimately fatal. In addi-
tion, silicosis can be associated with tuberculosis, lung can-
cer, renal disease, and nonmalignant respiratory diseases
(emphysema, chronic bronchitis, etc.) [2, 3]. The only way
of avoiding silicosis is through prevention of exposure to
respirable crystalline silica dust.
REGULATIONS
The current regulations for respirable crystalline silica dust
in metal/nonmetal mining are listed in Code of Federal
Regulations, Title 30, Chapter I, Subchapter K, Part 56 and
57, Subpart D with the current limits referenced in the
“TLV’s Threshold Limit Values for Chemical Substances
in Workroom Air Adopted by ACGIH for 1973.” As ref-
erenced in this document, for respirable crystalline silica
dust or quartz1, the current limit (as of 2023) is: .For total
dust (respirable and nonrespirable) the limit is .There is
a special category for silicates (1% quartz) where limits
are referenced in the document. If quartz is 1%, then
1. MSHA uses “quartz” for crystalline silica. This convention
will be used throughout the rest of the paper.