Occupational hygienist Jeremy Trotman writes about the advances and challenges in noise exposure reduction in the mining industry.
Noise levels and personal noise exposures in the mining industry are as diverse as the industry itself, which includes surface and subsurface, longwall, room?and?pillar and deep?shaft systems.
There is also a vast array of noisy equipment used to extract, transport and process the various ores. What further complicates noise management is the different compliance requirements between the states, particularly with respect to environmental noise standards. To simplify, I will focus on the issues that are common to many workplaces.
Firstly, meeting environmental noise standards is becoming more of a challenge for noisy industries that abut against residential or commercial zones due to what appears to be an increasing public awareness of noise and the ever?increasing urban expansion into what were once rural areas.
Meeting the challenges of low compliance thresholds (compared with occupational noise), the complexity of environmental standards that change with time, background levels and other noise characteristics, requires a high level of experience to accurately assess environmental noise emissions. The intricacies of the physics of assessing multiple potential noise sources, including the frequency and duration of each, requires specialist knowledge, measurement equipment and analysis software to assess the impact that industrial noise has on various sensitive receivers.
The good news is that we now have software capable of accommodating all the variables and performing the calculations required to predict noise levels at multiple receiver sites in great detail. This allows for the assessment of the efficacy of different noise controls and therefore the selection of cost?effective options. Fortunately, designing environmental noise controls can also have the additional benefit of reducing noise levels for employees using, or in the vicinity of, controlled equipment.
Occupational noise standards are simpler than environmental standards, but measurement and assessment of the former can be equally as complex in terms of the variability of noise sources, and there are exposure factors of noise frequency and duration to consider. The automation of many tasks and improvements in equipment (e.g. air?conditioned and acoustically insulated cabins) has produced big reductions in operators’ noise exposures. However, significant noise exposures still remain for maintenance and other personnel exposed intermittently to noisy equipment where exposure frequency and duration does not warrant treatments such as acoustic cabins.
For highly variable equipment (e.g. powered hand tools), exposures can be difficult to assess via a statistically valid sampling strategy due to limitations on time and resources available for noise exposure monitoring. This increases the reliance on professional judgement and consultation with people who know the site and its operations, equipment and conditions. It is also important to have the appropriate equipment, including noise dosimeters, to do the job correctly. Short?changing the noise assessment may make sense to an accounting spreadsheet, but only because this document will not suffer the communication, comfort and possible safety problems that will inevitably emerge from conservative recommendations due to inadequate data and inexperienced personnel.
Regulations in all Australian jurisdictions require the control of noise in accordance with a specified hierarchy. The terminology differs, but the intent is clear: elimination and engineering controls must be shown to be impracticable before resorting to hearing protection as the control measure for noise. Many situations where engineering solutions remain impractical still exist and the control solution often defaults down to hearing protection.
Hearing protection is bottom of the list for many reasons, but the principal reason is that it is an unreliable control measure, due partly to the need for correct selection and fit and also because it needs to be worn constantly. If employees do not use hearing protection the entire time when exposed to high noise levels, in many situations it is possible that the received noise dose can exceed applicable exposure standards, resulting in potential harm.
Generally, the more thorough the noise assessment, reduced is the number of employees who will find themselves having to wear hearing protection. Where hearing protection is used, the only reliable, empirical means of testing the efficacy of the hearing protection programme is with audiometric testing. People who have been involved in this area for many years consider audiometric testing to be one of the most productive services in the OHS area, delivered at a fraction of the cost of other less?effective interventions.
Arguments supporting this approach include:
- Occupational hearing loss, a shocking disability, which is entirely preventable at insignificant cost to employers, remains the worst or second?worst (in terms of compensation cost, a measure of population severity) occupational injury/disease in Australia.
- OHS equipment suppliers indicate that hearing protection remains the most prevalent and important control measure for noise. In many instances, this takes the form of ear plugs. The increase in the range and attenuation of earplugs has made them technically capable of protecting workers in relatively high?noise environments. Their handy size, disposability and, above all, price makes them an attractive option for employers. Practitioners agree that the overriding issues with ear plugs are: their correct fit, that training and perseverance are required to ensure correct fit, and that correctly fitted plugs can often be uncomfortable, at least for a period. There are many workplaces where, due to a variety of reasons, there is no training and no ongoing reinforcement of workers in the correct fitting of hearing protection.
- Audiometric assessments are the most powerful tool in the education of workers regarding the risks to them as individuals and the need to change their behaviour in relation to the selection, fit and use of hearing protection. The power of this comes from the one?on?one consultation with an independent, trained technician with access to specific results for the worker. Audiometric testing as the only effective monitoring process for the effectiveness of control measures, which doubles as a screening hearing test and a one?on?one consultation/training session, forms a critical part of the prevention process for around $20 per consultation.
- Removing the requirement for mandatory testing discriminates against certain workers in noisy jobs. Regulatory requirements are irrelevant to many larger or small, well?informed organisations who recognise the preventative value in audiometric testing, regardless of the regulatory position, and have a serious commitment to OHS. NSW WorkCover’s ambivalent policy of recommending, but not regulating audiometric testing sends a clear signal to those employers that they do not value hearing loss prevention, nor see the disability caused by hearing loss as significant. At the same time, this position gives a free kick to organisations willing to discount employee hearing for the sake of about $20 per person – less than the cost of a set of cheap hearing protectors.
- All workers exposed to hazardous noise should have the opportunity of regular audiometric testing with a one?on?one interview to explain their test results and warn of early signs of hearing loss and provision of referrals for further examination where required. This also provides the opportunity to reinforce the need for correct selection, fit, maintenance and constant use of hearing protection. This opportunity should not be left to the vagaries of employers’ interpretation of the requirements of Codes of Practice or other persuasive sub?regulatory requirements. It would be interesting to discover who WorkCover thinks will miss out under this system.
- If the decision to soften up audiometric testing requirements has been made on economic grounds, perhaps the economists have got it wrong. It wouldn’t be the first time. Audiometric testing has been shown to be a cost?effective health intervention. Dr David Goddard and Dr Geza Benke, senior researchers at Monash University’s well?regarded Department of Occupational and Environmental Medicine, report that audiometric testing or screening audiometry probably represents the best value in preventative health interventions. The safety net for those left without the benefit of early intervention will be the public health system, which subsidises hearing aids and future treatment costs that could have been eliminated or minimised with early intervention.
- Mandatory audiometric testing is entirely consistent with the biological monitoring requirements under the hazardous substances regulations where the required testing regimes are less well established, in some cases with no recognised substantive test available and where the links to measurable health outcomes for the specific substance exposures are less well established than the known benefits of screening audiometric testing.
In summary, we have made advances in noise exposure reduction, but some challenges remain. There is no doubt that hearing protection will continue to form an important part of our control solution kit for some time to come. Do yourself a favour and get experienced, well?equipped people to do your noise assessments. It may or may not save you money in the long run, but it will minimise the number of your people who will have to wear hearing protection. And where you use hearing protection, you really should have audiometric testing.
PROFILE
JEREMY TROTMAN
OCCUPATIONAL HYGIENIST
Jeremy is an OHS Professional with a wide technical competency skill set, over 20 years’ experience across a broad range of industry sectors, comprehensive OHS issues experience and specific experience in compliance and due diligence assessments. As a Certified Occupational Hygienist, SIA Chartered Fellow and Chartered OHS Professional, Full Member of the Human Factors and Ergonomics Society of Australia and Dangerous Goods Advisory Body, he has a good grasp of the technical issues required for broad due diligence assessments.
His experience in OHS spans the key areas of compliance including OHS, WHS and dangerous goods regulation, commercial, government and manufacturing industry sectors and the major utilities including water, electricity, rail and port operations. Jeremy has specific experience in challenging due diligence projects where the demands of timelines and data access require an analytical approach and sustained focus on material issues. Due diligence experience includes projects in the manufacturing and utility sectors the latest being as part of the Arup team involved in the due diligence assessment of a significant utility.
Occupational hearing loss, a shocking disability… remains the worst or second?worst occupational injury/disease in Australia.
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