Background: Workers are daily exposed to diesel exhaust (DE) and DPM due to the
continuous increase of diesel–powered vehicles in the underground mining environment. The
National Institute for Occupational Safety and Health (NIOSH) recommends that DE be
regarded as a “potential occupational carcinogen”. A great concern in the South African mining
industry is that there is currently no existing occupational exposure limits (OEL) for DPM.
Aim: To quantify the exposure of workers to DPM (that consists out of total carbon (TC): which
is a combination of elemental carbon (EC) and organic carbon (OC)) in the ambient air of
underground working environments. Also to compare different occupations exposure levels to
an international standard (the Mine Safety and Health Administration’s (MSHA) OEL for TC) as
South Africa has no proposed guideline or standard for occupational exposure to DPM and
finally to determine whether or not occupations working at mines with different mining methods
have different exposure levels to DPM.
Methodology: Workers personal exposure to DPM was monitored using the NIOSH 5040
method. A DPM sampler that consisted of a cyclone, a pre–packed SKC filter cassette (37 mm)
with impactor, tubing, label clips and a sampling pump was used. The flow rate was calibrated
at 2.0 litres per minute (L/min) for the sampling of sub–micrometer particles. The personal
sampler device was attached to the employee’s breathing zone for the duration of the work shift
(normal eight–hour time–weighted average (TWA) standard). A high risk group (workers
operating diesel–powered vehicles), a low risk group (workers working in the same mine,
sharing the same supplied air, but not operating these vehicles) and a control group (workers
working at a different mine with a different mining method) was monitored. The exposure levels
were evaluated and compared with the specific OEL mentioned previously.
Results: For the purpose of this study, TC exposure results were evaluated and not EC or OC.
All the occupations within their specific exposure group was exposed to TC. When the control
group’s exposures were compared with the high and low risk group exposures, a significant
difference was recorded (p–value = 0.0001). However when the high and low risk exposures
were compared with each other, no difference was recorded (p–value = 0.4405). When the
results of the various groups were compared with the MSHA OEL all the occupations from the
high and low risk group’s results were above the OEL, but only one occupation from the control
group exceeded the OEL.
Conclusion: It should be noted that all the occupations no matter the mining method / mine
was exposed to TC. The high and low risk exposure groups was however much higher than the
control group and a continues monitoring programme should be implemented for these
exposure groups. Their results exceeded the OEL, where the control group had much lower
exposure levels and only one occupation exceeded the OEL. Greater focus should be given to
the mechanized mining occupations since diesel–powered vehicles are used to perform their
core mining needs whereas at the conventional mine the use of these vehicles are limited.
Recommendation: Depending on the different occupations sampled various engineering
controls can be considered. Some include diesel oxidation catalysts (DOC), diesel particulate
filters (DPF) and diesel disposable exhaust filters (DEF) or also known as disposable diesel
exhaust filters (DDEF) which is very effective in removing DPM from the exhaust of dieselpowered
equipment. Education and training are also critical components to the success of a
diesel emission management programme and the last resort to be considered is the appropriate
personal protective equipment (PPE). South Africa should consider the implementation of
national standards in order to monitor the progress and success of the diesel emission
management programme implemented. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2012.
| Identifer | oai:union.ndltd.org:NWUBOLOKA1/oai:dspace.nwu.ac.za:10394/7057 |
| Date | January 2011 |
| Creators | Liebenberg, Marlize Maria Magdalena |
| Publisher | North-West University |
| Source Sets | North-West University |
| Detected Language | English |
| Type | Thesis |
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