ABSTRACT
Particulate matter is a significant health hazard to many
industrial workers, most especially those in the mining industry. Many
underground workers globally suffer from silicosis, cancer and other health
related effects due to prolonged exposure to respirable crystalline silica dust
and diesel particulate matter (DPM). In order to determine the possible
potential outbreak of these diseases at Chirano Gold Mines Limited (CGML), an
assessment of the levels of exposure of underground mine workers to
occupational respirable mine dust and DPM hazards were undertaken. The study
could not take into consideration the use of respirators as a control measure
thereby considering all the experimental findings as potential exposures.
Gravimetric air sampling pumps were used in collecting dust
and DPM samples for analysis. The respirable dust fraction were determined by
the differences in weight between the empty cassette filters and the used
filters whereas their crystalline silica content were determined by X-ray
diffraction using National Institute for Occupational Safety and Health’s
(NIOSH) analytical method 5040 as a guide. The DPM fraction of the samples was
also determined using NIOSH analytical method 7500. After analysis, the results
showed that the respirable dust exposures to the SEGs where far below American
Conference of Governmental Industrial Hygienist’s (ACGIH) PEL of 3.0mg/m3
over a Time Weighted Average (TWA) of 8 hours. However, high crystalline silica
contents were observed in some of the samples. The order of exposure to silica
is presented in a descending order as follows; Jumbo operators > Cubex
operators > Shotcretes operators > Solo operators>Blast men>Service
men > Diamond drillers > Bogger operators > Supervisors > Truck operators.
The results indicated that about 40.58% of the Sampled Exposure Groups (SEGs)
recorded levels higher than ACGIH’s recommended Permissible Exposure Limit
(PEL) of 0.05 mg/m3. DPM results also revealed a higher level of
exposure to SEGs as 48.68%, 11.84% and 39.47% of the SEGs fell within class A,
B and C respectively. Shotcrete operators recorded the maximum mean exposure
level of 287.99 µg/m3 whereas truck operators recorded the minimum
mean levels of 70.07 µg/m3. In a survey of 98 respondents majority
of them were aware of the presence of the particulate matter hazards and its
related effects. Nevertheless, a significant portion of the respondents had
very little knowledge of these. The research further ascertained that well
about 79.59% of the workers generally feel uncomfortable when using the FFp2
respirators during operational activities. This had a negative effect on the
use of their respirators during work. High silica values in little respirable
dust sampled suggests the presence of high silica bearing rocks underground
thereby putting workers at risk to contracting silicosis. High DPM levels also
suggest a high DPM generation by machines and equipment underground.
Inefficiency of available mitigation measures other than respirators is also a
factor of the high DPM exposure underground. From the study, if the current underground
PM generation levels remain unchanged, then an increased risk to respiratory
diseases silicosis, lung cancer as well as other related disease would occur.
CHAPTER ONE
INTRODUCTION
1.1 Overview of Mining Practices
Mining, a highly intensive operation that employs the use of
several intensive technologies with sophisticated machines is generally
regarded as among the most dangerous operations in the world (Grayson,
1999). The generation of varying levels of particulate matter, noise, heat,
vibrations amongst others is very conspicuous in a mine environment. They
result from the mining cycle which involves excavation, drilling, blasting,
bogging, hauling and crushing. Over the past decades, mining industries in
Ghana had little and weak measures towards health and safety of their employees
(Armah, 2015). Safety was seen as expensive and a measure
to reduce company’s revenue but instead, complied more on industrial
regulations to prevent legal suit against their operations (Staley,
1992). Nevertheless, environmental and health impacts associated with
mining are well noted in the world.
Particulate matter exposures have long been known to be a
serious health threat to workers in mines. Exceeding the exposure limits to
respirable silica dust and diesel fumes in the work environment can lead to the
development of varying health complications such as lung cancer, silicosis and
other pulmonary infections (Churchyard et al., 2004, NIOSH, 1992). Poor vision, irritating smells in the work
area are notable effects of Diesel Particulate Matter (DPM) emissions.
Crystalline silica, a common component of dust generated by mining activity
mostly as alpha quartz can have devastating health impact when over exposed to
higher level. According to the International Agency for Research on Cancer (IARC),
crystalline silica was identified as a suspected
probable cancer causing particles to humans (Grayson, 1999).
The degree of health implications associated with the
exposure to respirable mine dust and diesel particulate matter is mostly
dependent on the following significant factors; the chemical and mineralogical
content of the particulate matter inhaled, its quantity, particle size
distribution, structure and average duration of exposure (Yassin
et al., 2005). It has also been reported that freshly fractured silica
containing rock or soil is very toxic and highly reactive than stale dust (Wang and Banks, 1998). Once silicosis which develops after
exposure to high silica dust is contracted, they become incurable. As a result,
the ultimate aim of all industrial managers must be geared towards its
prevention by limiting workers exposure to the hazards at work. This can be
achieved by employing both engineering and administrative measure to eliminate
or reduce the emission of high Particulate Matter to recommended exposure
levels (REL). Silicosis may be acute, accelerated or chronic depending on the
average exposure levels and exposure duration of the victim (NIOSH, 1992).
The Mine Safety and Health Administration (MSHA) collaborated
with NIOSH in notifying general industry on silicosis in 1996 due to the high
incidence of silicosis in Pennsylvania among drill operators at surface mines (Rosenstock and Stout, 1998). With the
current worldwide concern and campaigns by varying stakeholders such as Ghana’s
IDMC, ACGIH, MSHA, EPA, OSHA, and NIOSH for the need for stringent measures towards
health and safety of all industrial workers and the environment without
compromising on costs, various control mechanisms have been instituted. The
establishment of health and safety standards, monitoring of effluence and
particulate matter generation for compliance purpose in most industries are
well recognized. These are to help address the general health and safety
concerns facing mine workers in order to ensure their
well-being. In Ghana, the Environmental Protection Agency (EPA) and
Inspectorate Division of Minerals Commission (IDMC) are among the key bodies
that ensure compliance to Environment, health and safety regulations in all
industries. Their activities involve monitoring the operations of all
industries by checking the level of effluence into the atmosphere, assessing
their pollution control measures, use of appropriate management practice,
enforcing compliance to environmental management plan among others.
At Chirano Gold Mining limited (CGML) many control measures
involving administrative and engineering controls are in place. Underground
workers are first inducted before working. Several dust control measures are
used to limit particulate matter exposures in the occupational work place. Workers
of CGML are further subjected to scheduled health screening and monitoring
exercise against potential health disorders. Such exercise involves; lung
function test, tuberculosis test as well as others medical studies in relation
to the possible health disorders that may arise from their work types. Despite
all the PM mitigation plans instituted, the presence of the hazard is very
conspicuous thereby requiring in-depth investigations into how to tackle the
hazard appropriately.
1.2 Problem Statement
Underground mining operations in CGML evolve large volumes of
dust and diesel fumes to the work area exposing workers to potential health
hazards through engine exhaust and rock breaking. Bio et al.
(2007) Has stated that for every quantity of respirable gold mine dust
collected, about 30% of free silica exists and their inhalation could trigger
the formation of the Chronic Obstructive Pulmonary Disease (COPD). He further
reported that, the development of chronic silicosis could be associated with
continuous respiration of crystalline silica at moderate to high levels of 0.05-0.1 mg/m3 over a long period
of years (Armah, 2015). Nearly 200-300 deaths were reported
each year during the period 1992–1995 from silicosis in the USA (Sherson, 2002). High exposure to DPM can result in cancer
in humans and other fatalities.
1.3 Justification
Even though CGML works assiduously in mitigating PM
generation throughout the mine, dust and DPM hazards still exist in underground
occupational areas. There have been reported cases of silicosis and other PM
related health effects in some other mines which could occur at CGML if
exposure levels are high above the recommended PEL. Silica (quartz) is a common
constituent of some soils accounting for about 28.5 % weight of the earth crust
and occurs widely in goldmines. CGML is committed to providing all the
necessary supports to help successfully conduct the research so that safe
mining which is a priority of all stakeholders will be achieved. Considering
the aforementioned challenges in the mining industry, this study is vital to
provide CGML with vivid underground occupational conditions to efficiently protect
its workers from PM hazards.
1.4 Aim and Objectives
This study aims to ascertain the levels of exposure of
underground mine workers to respirable mine dust and diesel particulate matter
hazards.
The specific objectives are;
To determine the potential exposure levels of workers to
respirable dust and DPM.
To determine the sources of dust and DPM generation
underground.
To identify the category of workers
with high risk to contracting silicosis, lung cancer and other pulmonary
diseases due to silica and DPM exposures.
To identify the available mitigation measures to dust
pollution at Chirano Mines.
To determine workers awareness to the presence and adverse
effect of particulate matter pollution to their health.
To establish workers attitude in relation to the use of
respirators during work.
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