December 15, 2017

The hidden hazards of high decibels  


 Mine workers are likely to lose their hearing ability by the time they retire, given the lack of, or poor noise management practices, in mines. It’s not too little too late – the situation can be salvaged – it’s entirely in the hands of mines.

One of the areas in which it is feared African mines might be tempted to sacrifice as they frantically struggle to cope with the effects of the commodities price slump expenditure on their bottom-line is on Occupational Health and Safety initiatives, especially Noise-Induced Hearing Loss (NIHL).

Understandably, as mines leap from one occupation health and safety calamity to another as a result of laxity (according to credible press reports), NIHL initiatives could be overshadowed by other equally pressing concerns. But it is a burden which mines can only neglect at their own peril, as regulations are unequivocal about compliance.

Legislation in different countries obliges mines to uphold occupational and health practices religiously. A classic case is in South Africa, where  in terms of the Mine Health and Safety Act (Department of Minerals and Energy, 1996), Instruction 171 (COIDA, 2001) and South Africa National Standards (SANS10083:2007, 2007) the employer is obliged to establish and maintain a system of medical surveillance for all employees in any working place where the equivalent, continuous A-weighted sound pressure level, normalised to an 8 hour working day or a 40 hour working week exceeds 85 dB (A).

Additionally, Legislation (Instruction 171) makes it compulsory that a baseline audiogram is conducted for all individuals within two years after this legislation had been published and within 30 days for new employees who had not worked previously.

Short term gains, long term losses

It is evident that the price of non-compliance could be much higher than it is usually imagined.  Mines may face challenge on two fronts. First, there could be a long-term cost of short-term gains accrued from cutting down on noise management initiatives. Affected employees might not be as productive as they once were, unwittingly resulting in low revenue. Secondly, there even could be the possibility of costly litigation from authorities and bad publicity. Indeed, the stakes couldn’t have been higher!

The enormity

Why is there much ado on NHIL? The enormity of NIHL is not exaggerated. The World Health Organisation (WHO), under its Programme for the Prevention of Deafness and Hearing Impairment, after carrying out an assessment of the global disease burden from occupational noise, found that noisy workplaces have a heavy impact on health around the world. In addition, occupational noise contributes 22 per cent of disabling hearing loss in men.

Hearing loss gives rise to speech recognition problems in difficult environments, results in the reduction of ability to detect and identify sounds. And good hearing is critical in the mining environment. Imagine what could happen to an employee with impaired hearing in the event of failing to respond to alarm signals during an accident!

An overlooked hazard

Noise-related worker practices and audiometric testing done at various mine sites corroborate that noise induced hearing loss is one of the most prevalent occupational illnesses in mines across the continent. This fact was highlighted by a study (published in African Health Science 2013 Dec; 13(4): 899–906) carried out at mine sites in Zimbabwe to establish the extent of NIHL by three researchers, A. Chadambuka, F. Musasa and S. Muteti found that the majority attributed NIHL to noisy work environment. Levels of noise which could be described as “excessive” was identified in Plant Processing (94 dBA), underground mining (102 dBA) and underground workshop (103 dBA).  It has to be noted that the threshold in mines is around 85 dBA.

A more or less similar pattern emerged in study the University of Pretoria set out to determine the prevalence and nature of NIHL and to evaluate the criteria for determining hearing impairment in South African gold miners.

Intriguingly, though not entirely surprising, the level of compliance with noise exposure monitoring in African mines is disparate (noticeably, it is better in big miners than in junior miners). This is due to the fact that big miners have money to burn while junior miners have limited financial resources. Even in some bigger mines, programmes are only run half-heartedly, being adopted merely to be on good books with relevant authorities. One of the oversights that emerges is lack of engineering control measures in place to reduce noise levels.

A Necessity

In view of the above mentioned conditions, hearing conservation programmes to protect employees against NIHL should be a pre-requisite. The conclusion of the study conducted in Zimbabwe suggests how mines could approach this challenge: “The hearing conservation must begin by providing each individual with information. The mine management should install engineering controls in areas exceeding permissible noise levels. Alternatively management may meanwhile use administrative controls and adhere to permissible exposure limits according to the noise regulations.”

Manufacturers join the fray

For those too occupied with other developments to notice: some manufacturers are incorporating technologies that enable their products to produce low sound decibels, making compliance with noise regulations in some mining environments easier. This can be seen in recent models of haul trucks from Duratray which is being used at a Moolarben Coal Complex in Australia. While a normal dump truck produces anything from 132 dB to 146 dB, a dump body from Duratray truck body noise ranges from 127 dB to 139 dB, reflecting a significant reduction. Increasingly, this feature is being used in other products.

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