| Summary: | There is limited information available on the exposure of workers to NOx and NH3 from blasting
fumes in the underground mining setup. This study is therefore motivated to improve the
working conditions of underground mine workers handling these explosives, thus minimizing
their potential exposure to NOx and NH3. Only a few epidemiological studies are available
addressing the cumulative exposure of underground mine workers to blasting fumes, as well as
the incidents of so–called gassing cases, although such cases do occur on a regular basis in an
underground mining setup. Underground mine workers undertaking handling, transportation
and charge up of explosives are potentially exposed to blasting fumes on a daily basis and
cumulative exposure is therefore a major risk factor and could lead to serious health effects.
The Mine Health and Safety Regulations of the Mine Health and Safety Act (Act No. 29 of 1996)
has recommended limits for the components of blasting fumes, but there is an absence of a limit
specifically set for blasting fumes as a single gas exposure. In blasting fumes there are
mixtures of gases that can cause respiratory and systemic health effects at much lower levels.
To determine the exposure of underground mine workers to NOx and NH3 from blasting fumes
and ANFO, samples were taken for a period of three hours and then time weighted to an 8–hour
time weighted average (TWA) and compared to existing standards.
Active sampling and passive diffusive sampling were conducted to determine the difference of
occupational exposure levels to NOx and NH3 among underground mine workers and surface
workers. Samples were taken 12 hours after the previous blast due to work related limitations
making it impossible to sample night shift workers.
Active sampling for a duration of 180 minutes, time weighted to an 8–hour exposure, indicated
that occupational exposure to blasting fumes of underground mine workers responsible for
charge up did not exceed the OELs of the Regulations of the Mine Health and Safety Act (Act
No. 29 of 1996). Passive diffusive sampling for a duration of 180 minutes, time weighted to an
8–hour exposure, indicated that occupational exposure to blasting fumes of three underground
mine workers responsible for charge did exceed the OELs of the Regulations of the Mine Health
and Safety Act (Act No. 29 of 1996).. There was a significant positive correlation between
personal exposures to NH3 between the two measurement methods. There was a positive,
insignificant correlation, as well as a strong agreement between personal exposures to nitrogen
dioxide (NO2). This correlation proved that any of these two approved conventional measurement methodologies could be used to determine the exposure of underground mine
workers to NH3 or NO2.
Limitations of the study as well as recommendations for future studies are also presented in
Chapter 5.
This study however does not exclude the effect of cumulative exposure to blasting fumes over
an extended period of time. Short term exposure is also a major concern when working with
toxic fumes and should be determined in future studies. === Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2011.
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