Noise emissions and exposures among drill operators and assistants in an opencast mine in South Africa
Date
2024
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Witwatersrand, Johannesburg
Abstract
Background:
Noise is defined as ‘undesirable’ or unwanted sound and is one of the most common occupational hazards in the workplace. Millions of workers are exposed to workplace noise that is potentially damaging to hearing. Noise also creates psychological stress, interferes with communication, concentration and can reduce productivity.
Objective:
The objectives of this study were to compare noise exposures between drill operators and assistants, to compare the noise emitted by drilling machines with noise exposures, and to identify risk factors associated with noise exposure in these workers.
Methods:
A quantitative cross-sectional study was conducted at an opencast Platinum Group Metals (PGM) and chrome mine in South Africa. Personal noise measurements were recorded throughout the work shift, for 40 drill operators and 20 assistants, using a noise dosimeter. The noise emitted from 10 drilling machines was also measured, using a sound level meter. Information on age, years worked as a drilling operator/assistant, and specific drilling machines operated, was collected. Information about the drilling machines, such as the area where drilling was done, the type of drill and material being drilled, and machine hours was also collected. Noise exposures for drill assistants and drill operators were compared, using an independent two-sample Student t-test. The two-paired Student t-test was used to test for the differences between noise emissions and noise exposures for the drill operators and assistants. To identify risk factors associated with noise exposure, a multivariable linear regression model was used. The independent categorical variables were age, time in job, shift cycle, job title, machine hours, material drilled, machine type, and deployment area. The independent continuous variables were noise inside the machine cab, noise outside the machine cab window, and noise at 1 m from the drilling machine. The dependent variable wasnoise exposure for drill operators and assistants.
Results:
The majority (n=40, 67.7%) of the study participants were drill operators; there were 20 (33.3%) drill assistants. Most (n=14, 70.0%) of the drill assistants were 35 years or younger, while most of the drill operators (n=19, 47.5%) were 36 – 45 years of age. The drill assistants were exposed to significantly higher mean TWA noise levels than the drilling operators, viz. 92.0 and 81.7 dBA, respectively. All drill assistants (n = 20) and 32.5% (n = 13) of the drill operators were exposed to mean TWA noise levels ≥85 dBA. There were statistically significant differences between the drilling machine noise emissions (both inside and outside the drilling machine cab) and the noise levels to which both groups of workers were exposed. Noise exposure levels were significantly associated with job title, machine hours, noise emissions outside the cab window, and the deployment area.
Conclusion:
Drill assistants were exposed to higher noise levels than drilling operators. The integrity of the cab may reduce noise exposure for the drilling operators. The noise emissions measured outside the cab window of the drilling machine were higher than those inside the cab and 1 m from the drilling machine. This indicated the importance of ensuring that cabs are designed to ensure reduced noise exposure for the drill operators. Drill assistants need to understand that maintaining a distance away from the drilling machine is important to reduce noise exposure levels. Knowing what factors are associated with noise exposure allows the mine to implement control measures to reduce such exposures. Controlling noise at the source is important, and employing detection tools for noise, such as real time monitoring, is necessary to record accurate employee exposures to assess if controls are effective
Description
This research is being submitted for the fulfillment of the requirements for the degree of Master of Public Health (Occupational Hygiene) in the Faculty of Health Sciences, School of Public Health, University of Witwatersrand, Johannesburg 2024
Keywords
Noise, Noise in Mining, Drill Operators, UCTD
Citation
Zamisa, Thulile Senzekile. (2024). Noise emissions and exposures among drill operators and assistants in an opencast mine in South Africa [Master’s dissertation, University of the Witwatersrand, Johannesburg]. WireDSpace. https://hdl.handle.net/10539/42713