2
the respirable dust limit becomes a total dust standard
of 10 mg/m3 for those mineral dusts listed in Appendix
E [4]. Currently (in 2023), the Mine Safety and Health
Administration is proposing a new respirable quartz dust
standard which will change these limits to 50 µg/m3 with a
25 µg/m3 action limit [3].
Currently for either coal or metal/nonmetal, operators
do not sample for respirable quartz dust. The MSHA inspec-
tors complete all sampling for respirable quartz dust. Coal
sector samples for respirable coal mine dust are made on a
prescribed schedule as laid out in CFR Title 30, Chapter I,
Subchapter O, Part 71. Sampling requirements for dust in
metal/nonmetal seem somewhat ambiguous as referenced
in Part 57 and Part 56, Subpart D, where Part 56.5002 and
Part 57.5002 state “Exposure monitoring. – “Dust, gas,
mist, and fume surveys shall be conducted as frequently as
necessary to determine the adequacy of control measures.”
In July 2023, MSHA proposed a new silica dust rule
that will apply to the mining industry. The proposed rule-
making can be found on the Federal Register, Docket
No. MSHA-2023-0001 “Lowering Miners’ Exposure to
Respirable Crystalline Silica and Improving Respiratory
Protection” [3]. This proposed rule intends to lower the
respirable silica dust limit from 100 µg/m3 to 50 µg/m3
with a 25 µg/m3 action level, require operator sampling,
necessitate personal protective equipment (respirators)
when silica levels are exceeded, add additional medical sur-
veillance of miner by operators, etc. This rule will amplify
the demand for research in real-time respirable dust mea-
surement, particularly for respirable crystalline silica dust in
order to allow mine operators to operate within compliance.
To assist mine operators maintain compliance with the
regulatory limits for respirable coal mine dust and respirable
silica dust, NIOSH has maintained a portfolio of research
for developing and improving dust controls used in mine
operations, developing new and upgrading existing mea-
surement methods for real-time dust monitoring, develop-
ing and analyzing surveillance databases, and investigating
dust characteristics to determine the chemical makeup
and physical dimensions of respirable dusts. Through this
research NIOSH can provide important information and
interventions that can reduce exposure to respirable dusts
to miners.
NIOSH FOCUS ON RESPIRABLE DUST
The U.S. Bureau of Mines (USBM), and later NIOSH,
have funded research for preventing respiratory occupa-
tional diseases CWP and silicosis. The Bureau of Mines was
established in 1910 and early dust research was conducted
for controlling dust from underground drilling operations
in metal mines. Beginning in the 1950s research on roof
bolting drilling operations in coal mines commenced [5].
The Federal Coal Mine Health and Safety Act of 1969
(Public Law 91-173) established respirable dust level limits
for the first time. This regulation provided additional impe-
tus for conducting research on respirable dust in the min-
ing industry. In 1996, the mining health and safety research
programs of the USBM were transferred to NIOSH. Since
that time NIOSH has been funding research on mine
safety and health including a focus on respirable dust that
emphasizes developing new or improving current control
methods to prevent exposure to respirable dusts. Included
are research in developing measurement methodologies,
particle characterizations, etc. NIOSH funds this research
both internally and externally through contracts.
INTERNAL RESEARCH
The research conducted internally within NIOSH is broad
and impacts the entire range of the mining industry (coal,
metal/nonmetal, stone, sand &gravel) for both surface
and underground operations. The research topics are too
numerous to include in this summary. Since the publica-
tion of the proposed silica rule by MSHA, an area of con-
cern in the rule is the measurement of silica. Therefore, only
research on the continuous personal dust monitor (CPDM)
and field analysis of silica tool (FAST), two focus areas of
interest to respirable dust, are summarized. The CPDM
is a respirable coal mine dust monitor that provides near
real-time respirable coal mine dust concentrations, in that
the concentrations provided are averaged over the previous
30-minute time period [6]. While the FAST method for
silica analysis, though not real-time (currently there is no
commercially-available device for real-time measurement of
respirable silica dust) it is a step forward in advancing tech-
nology for real-time measurement of respirable silica dust.
A starting point for the research for both CPDM and
FAST began with the USBM. The USBM initiated basic
research on different technologies for use as a short-term
dust monitor in underground mines (beta attenuation, light
scattering, mass). This work was conducted from 1970–
1990, reviewing the Tyndallometer –German, SLIMSIN –
Britain, RAM-1 –US (precursor to the personal DataRAM
pDR-1000AN Monitor (Thermo Scientific), and Sibata
P5 –Japan. From the review, the USBM concluded that
direct mass measurement was most feasible and accurate
for underground mining environment [7].
the respirable dust limit becomes a total dust standard
of 10 mg/m3 for those mineral dusts listed in Appendix
E [4]. Currently (in 2023), the Mine Safety and Health
Administration is proposing a new respirable quartz dust
standard which will change these limits to 50 µg/m3 with a
25 µg/m3 action limit [3].
Currently for either coal or metal/nonmetal, operators
do not sample for respirable quartz dust. The MSHA inspec-
tors complete all sampling for respirable quartz dust. Coal
sector samples for respirable coal mine dust are made on a
prescribed schedule as laid out in CFR Title 30, Chapter I,
Subchapter O, Part 71. Sampling requirements for dust in
metal/nonmetal seem somewhat ambiguous as referenced
in Part 57 and Part 56, Subpart D, where Part 56.5002 and
Part 57.5002 state “Exposure monitoring. – “Dust, gas,
mist, and fume surveys shall be conducted as frequently as
necessary to determine the adequacy of control measures.”
In July 2023, MSHA proposed a new silica dust rule
that will apply to the mining industry. The proposed rule-
making can be found on the Federal Register, Docket
No. MSHA-2023-0001 “Lowering Miners’ Exposure to
Respirable Crystalline Silica and Improving Respiratory
Protection” [3]. This proposed rule intends to lower the
respirable silica dust limit from 100 µg/m3 to 50 µg/m3
with a 25 µg/m3 action level, require operator sampling,
necessitate personal protective equipment (respirators)
when silica levels are exceeded, add additional medical sur-
veillance of miner by operators, etc. This rule will amplify
the demand for research in real-time respirable dust mea-
surement, particularly for respirable crystalline silica dust in
order to allow mine operators to operate within compliance.
To assist mine operators maintain compliance with the
regulatory limits for respirable coal mine dust and respirable
silica dust, NIOSH has maintained a portfolio of research
for developing and improving dust controls used in mine
operations, developing new and upgrading existing mea-
surement methods for real-time dust monitoring, develop-
ing and analyzing surveillance databases, and investigating
dust characteristics to determine the chemical makeup
and physical dimensions of respirable dusts. Through this
research NIOSH can provide important information and
interventions that can reduce exposure to respirable dusts
to miners.
NIOSH FOCUS ON RESPIRABLE DUST
The U.S. Bureau of Mines (USBM), and later NIOSH,
have funded research for preventing respiratory occupa-
tional diseases CWP and silicosis. The Bureau of Mines was
established in 1910 and early dust research was conducted
for controlling dust from underground drilling operations
in metal mines. Beginning in the 1950s research on roof
bolting drilling operations in coal mines commenced [5].
The Federal Coal Mine Health and Safety Act of 1969
(Public Law 91-173) established respirable dust level limits
for the first time. This regulation provided additional impe-
tus for conducting research on respirable dust in the min-
ing industry. In 1996, the mining health and safety research
programs of the USBM were transferred to NIOSH. Since
that time NIOSH has been funding research on mine
safety and health including a focus on respirable dust that
emphasizes developing new or improving current control
methods to prevent exposure to respirable dusts. Included
are research in developing measurement methodologies,
particle characterizations, etc. NIOSH funds this research
both internally and externally through contracts.
INTERNAL RESEARCH
The research conducted internally within NIOSH is broad
and impacts the entire range of the mining industry (coal,
metal/nonmetal, stone, sand &gravel) for both surface
and underground operations. The research topics are too
numerous to include in this summary. Since the publica-
tion of the proposed silica rule by MSHA, an area of con-
cern in the rule is the measurement of silica. Therefore, only
research on the continuous personal dust monitor (CPDM)
and field analysis of silica tool (FAST), two focus areas of
interest to respirable dust, are summarized. The CPDM
is a respirable coal mine dust monitor that provides near
real-time respirable coal mine dust concentrations, in that
the concentrations provided are averaged over the previous
30-minute time period [6]. While the FAST method for
silica analysis, though not real-time (currently there is no
commercially-available device for real-time measurement of
respirable silica dust) it is a step forward in advancing tech-
nology for real-time measurement of respirable silica dust.
A starting point for the research for both CPDM and
FAST began with the USBM. The USBM initiated basic
research on different technologies for use as a short-term
dust monitor in underground mines (beta attenuation, light
scattering, mass). This work was conducted from 1970–
1990, reviewing the Tyndallometer –German, SLIMSIN –
Britain, RAM-1 –US (precursor to the personal DataRAM
pDR-1000AN Monitor (Thermo Scientific), and Sibata
P5 –Japan. From the review, the USBM concluded that
direct mass measurement was most feasible and accurate
for underground mining environment [7].