People working in the quarrying and mining industries face a number of occupational health challenges including the debilitating effects of noise-induced hearing loss. The Australian Institute of Occupational Hygienists’ Beno Groothoff gives some sound advice on mitigating the effects of noise on workers’ exposed to it.
Quarrying and mining are notoriously noisy activities, particularly underground mining. Occupational noise in mining as a significant hazard has been well-established, in that it has been known for a very long time that mining noise varies from loud to excessively so.
Many mining companies spend considerable efforts and resources on mitigating both occupational and environmental noise. The question is how to effectively evaluate, communicate and control the noise. This article aims to provide some answers for effective noise management.
EVALUATING MINING NOISE
For the evaluation of mining noise, sound level measuring instruments must be used in accordance with relevant Australian Standards. For occupational noise management these are the AS/NZS1269-2005 five-part series with the exception of Part 4 which is of 2014. For environmental noise this would be the AS 1055-1997 three-part series. For sound level measuring instruments this would be AS IEC 61672.1-2004 electroacoustics-sound level meters, Part 1: Specifications.
These standards are normally called up in the relevant legislation and therefore form part of it and must be complied with. This also means that sound level meter apps used on smartphones cannot be used for serious measurements or attempting to demonstrate legal compliance. They can only be used as indicators to alert people that noise may have to be assessed with proper instruments. With underground mining there may be additional requirements that the instruments must be intrinsically safe.
Suitable sound level measuring instruments consist of Class 1 integrating sound level meters and so-called noise dosemeters. The former are normally used by an assessor to measure noise and observe the conditions and activities, while the latter are normally worn on a worker for the duration of a shift. Recent years have seen the introduction by several manufacturers of noise dose badges, some of which are also available as intrinsically safe. These badges are small and can be conveniently worn by a worker without interfering with the daily activities.
Noise exposure measurements are required where there is a likelihood of workers being exposed to hazardous noise, i.e. noise that has the potential to exceed exposure limits or target levels. Such measurements must be conducted at the workers’ ears otherwise they cannot be used to demonstrate compliance with an exposure limit, e.g. the LAeq,8h limit.
Area noise measurements are useful for identifying specific noise sources, similar exposure groups (SEGs), delineating hearing protection zones, checking the effectiveness of noise control measures or compiling noise contour maps.
Many modern sound level measuring instruments have capabilities of audio recordings of the noise measured; log noise histories, record assessor comments and GPS locations, and download the obtained data to software programs to post-evaluate and manage workers’ exposure.
There are also possibilities to store data in ‘the Cloud’ so the data can then be shared with other computers anywhere in the world. Mining activities often also create some noise impact on surrounding communities and this must be kept in check. There are continuous noise monitoring programs available that can be utilised to demonstrate not only compliance with noise limits, but also enable maximum mining efficiency within the noise constraints and transparency to the surrounding community, which may help to develop trust and tolerance.
IDENTIFYING RISK OF NOISE IN THE WORKPLACE
A commonly used first indicator that workplace noise may be dangerous is when you must raise your voice to be heard by a worker who is about a metre away. If so, that noise is potentially toxic and must be managed through a risk management process. There are two important aspects to risk management – what the legislation requires and what information is available.
The legislation requires a process of hazard identification, risk evaluation and analysis, control, and monitoring and review. Information should be obtained from internal sources, such as workers and supervisors, historical data, exposure monitoring and health surveillance, and from external sources, such as noise data from manufacturers of equipment, experts, research and standards such as AS/NZS ISO 31000:2009 Risk Management – Principles and Guidelines, and the AS/NZS 1269:2005 Occupational Noise Management series.
The mining industry typically works 12-hour shifts with many shifts also worked longer than the normalised five-day week period. Because of the 12-hour shifts, the recuperation period between shifts is reduced from 16 hours to 12 and thus creates a greater risk to worker health than if eight-hour shifts were worked.
The increased risk must be accommodated in any risk management program. AS/NZS 1269:1-2005 provides guidelines on how to mitigate the increased risk. In essence this comes down to adding 1dB to the eight-hour normalised shift noise to mitigate the possible temporary threshold shift (in hearing) effect.
HEALTH EFFECTS OF NOISE
Loud noise creates a range of health effects, of which the most obvious one is noise induced hearing loss (NIHL). According to Safe Work Australia (2013) in 2010-11, one quarter of workers’ compensation claims for miners was for deafness. Another common auditory effect associated with loud noise exposure is tinnitus (ringing in the ears). Both NIHL and Tinnitus are irreversible.
The problem with NIHL is not that the affected worker is deaf, as typically experienced with other forms of deafness. The problem is that the NIHL affected worker can hear well but has difficulty understanding verbal communication because high-pitched consonants like S, T, K and C, and high-pitched sounds such as Ch, St, Sh, Pf, and Th, particularly in women and children’s voices, cannot be heard.
This leads to misunderstanding in conversations. In the work situation the inability to hear high-pitched sounds can lead to misinterpretation of instructions and, more seriously, may become potentially life-threatening when alarm sounds cannot be heard. NIHL is incredibly frustrating and very socially isolating.
Loud noise creates ‘noise stress’ by interfering with the worker’s ability to communicate and concentrate. In the long term this can lead to fatigue, irritability, being uptight, decreased feelings of wellbeing and sleep disorders.
Contrary to some common beliefs the body does not get used to noise, but the autonomous nervous system adapts its biological functions by increasing heart rate and blood pressure and releasing adrenaline, noradrenaline and cortisol (the fight or flight response). In the longterm this will lead to cardiovascular disorders including high blood pressure and heart disease.
These health effects impact negatively on the affected worker’s ability to participate in social and occupational life. Communication with family, friends and colleagues is difficult and social isolation follows.
Exposure to industrial chemicals such as lead, solvents, carbon monoxide, or some medications like antibiotics and aspirin, may cause hearing loss and are called ototoxins. In combination with noise exposure they may cause worse hearing loss than noise alone.
The mining industry employs a large female workforce who may be doing work on equipment, such as haul trucks. Many of these women may be of childbearing age and pregnancy may create some health risks for both the woman and the foetus, which must be considered.
Foetal hearing is completely formed by about 28 weeks of gestation. As many women tend to work, for various reasons, too close to the final stages of their pregnancy, the high level noise exposure may have an effect on foetal hearing. More research is needed on this aspect, although a recent Swedish study by Selander et al (2015), supports the notion.
The general consensus is that there can be adverse effects on the newborn where the mother has been exposed to elevated noise levels. The main adverse effect of occupational noise exposure, noted by many retrospective studies, is a decrease in birth weight, either as small for gestational age and/or intrauterine growth restriction (Di Corletto, E., & Di Corletto, R. 2015).
The above information is but a summation of several effects from occupational noise exposure. There are however, other effects that need to be considered as they may interact.
In this regard the reader is referred to the above authors’ paper which provides more detailed information on pregnancy from occupational exposures to not only noise, but also heat and whole body vibration.
CONTROL OF NOISE IN THE MINING INDUSTRY
For both the organisation and noise-affected workers there is usually an economic cost involved in the form of increased worker absenteeism and turnover, reduced performance and therefore reduced productivity, and fewer opportunities for a worker to progress to higher paid jobs. Low noise environments therefore create benefits for both the organisation and the workforce.
To be successful in mitigating noise a documented noise management plan needs to be implemented. Such a plan has several important aspects, e.g. management responsibilities, target noise levels, performance indicators, time frames, risk identification and control through the hierarchy of controls, noise monitoring by competent persons, record keeping, periodic monitoring and reviews. These are just the main headings under which, depending on local circumstances and conditions, a number of sub-headings should be put in place and responsibilities be assigned for each.
Noise control opportunities in mining and quarrying may identify opportunities for noise elimination and/or substitution, but generally consist of engineering and administrative control measures. Noise mitigation can also be achieved through the mandatory use of personal protective equipment (PPE). Usually a combination of all three options is required.
… you do not go out on a sunny day wearing welding goggles, but you wear sunglasses to take the glare out of your eyes and enable seeing where you go. Similarly with noise you must be able to communicate and hear warning signals.
With regards to administrative noise control, a recent paper by Worland (2015) indicates that generally noise data from manufacturers of mining equipment is either non-existent or of such poor quality that it is unhelpful with Buy Quiet programs.
Hearing protectors (HPs) do not control workplace noise. Through the hearing protector the noise entering the worker’s ears is reduced to a safe level, if selected and worn correctly.
HPs should be worn where hazardous noise levels exist in the workplace that cannot be reduced through higher order controls or until such times that noise levels have been reduced to non-hazardous levels.
HPs should be selected based on workplace noise level, the worker’s hearing ability, ear canal size, fit comfort and preference, and possible interference with other PPE that may have to be worn at the same time. HPs should not be selected on the basis of “the higher the rating the better the protection” as this introduces other potential health and safety hazards by blocking out too much noise. The analogy is that you do not go out on a sunny day wearing welding goggles, but you wear sunglasses to take the glare out of your eyes and enable seeing where you go. Similarly with noise you must be able to communicate and hear warning signals.
Another important part of a noise management plan consists of audiometric testing of workers. Audiometric testing by itself is not effective in preventing NIHL, but as part of a comprehensive noise management plan it can be successfully used to ascertain whether or not controls are working and to identify emerging risk to a worker’s health and hearing.
Audiometric testing should be provided at least every two years to workers who are exposed to excessive noise and/or ototoxic agents, or the organisation’s noise target level. Where the eight-hour exposure exceeds LAeq,8h 100dB(A), more frequent audiometric testing may be required.
Two types of testing are conducted – the Reference Test, this is the initial test performed upon commencing employment, after a period of 16 hours in quiet, and the Monitoring Test, which is performed when the worker has been exposed to workplace noise but with the use of HPs.
The theory is that the tests should not show a difference when the worker is protected by the correct use of a hearing protector. Test results should be discussed with the worker and explained in simple terms. Where there are significant differences, as indicated in Clause 4.10 of AS/NZS 1269:4-2014, the worker should be referred to an audiologist or ear, nose and throat specialist for further investigation.
It is imperative that the background conditions in the test facility, e.g. sound booth, meet the requirements of AS/NZS 1269:4-2014 to prevent external noise interfering with the audiometric test proceedings.
Australian Institute of Occupational Hygienist
The Australian Institute of Occupational Hygienists (AIOH) defines occupational hygiene as “the art and science dedicated to the anticipation, recognition, evaluation, communication and control of environmental hazards in, or arising from, the workplace that can result in injury, illness, impairment, or affect the wellbeing of workers and members of the community…” Members of the AIOH are trained and educated in many aspects of occupational hygiene and many are Certified Occupational Hygienists (COH). They are competent to conduct noise monitoring and surveys of noise exposure, and make recommendations for its management and control.
M.Hlth.Sc, Grad Dip, OH&S. Dip, Mech Eng. FAIOH, COH, M.A.A.S
Beno has been working in the fields of environmental pollution control, occupational hygiene, and health and safety since 1970. In Queensland he worked in private practice and government positions in both environmental protection and workplace health and safety areas. He provided advice to Safe Work Australia on noise and vibration issues pertaining to the current Work Health & Safety Legislation. Beno is a member of the AV10 Committee of Standards Australia on occupational noise and vibration.
As managing director and principal hygienist of Environmental Directions Pty Ltd, he has written and presented training courses on Occupational and Environmental Noise and Human Vibration Management for Brüel & Kjær Australia. He has also worked as senior lecturer and course coordinators at the Queensland University of Technology’s School of Public Health and Social Work, teaching Occupational Health & Safety Management, and Occupational Hygiene and Toxicology to Postgraduate and Masters Students.
1. Di Corletto, E., & Di Corletto, R. (2015, December). Are you adequately protecting working mothers? A review of key reproductive workplace physical hazards associated with pregnancy. Paper presented at the 33rd Annual Conference & Exhibition of the Australian Institute of Occupational Hygienists Inc.
2. QGN 22 Guidance Note for Management of Noise in Mines https://www.dnrm.qld.gov.au/__data/assets/pdf_file/0006/240369/qld-guidance-note-22.pdf
3. Selander, J., Albin, M., Rosenhall, U., Rylander, L., Lewné, M., and Gustavsson, P. (2015), Maternal Occupational Exposure to Noise during Pregnancy and Hearing Dysfunction in Children: A Nationwide Prospective Cohort Study in Sweden, Environ Health Perspective DOI: 10.1289/ehp.1509874, Advance Publication: Not Copyedited; http://ehp.niehs.nih.gov/15-09874/#tab1
4. Safe Work Australia, (2013), Compendium of workers’ compensation statistics Australia 2010-11, Safe Work Australia, p83. http://www.safeworkaustralia.gov.au/sites/SWA/about/Publications/Documents/766/Compendium%202010-11.pdf
5. Worland, S. (2015, December). Challenges of implementing a Buy Quiet program in Australia in 2014. Paper presented at the 33rd Annual Conference & Exhibition of the Australian Institute of Occupational Hygienists Inc.
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