Ensuring the Effectiveness of Hearing Protection in the Workplace

The Health Risks of Excessive Noise in Australian Industries

Over 1.1 million Australians are estimated to be exposed to hazardous noise levels in the workplace on a daily basis.¹ Protecting workers from excessive noise exposure is rising to the forefront of occupational safety issues due to the wide range of Australian industries where noise poses a significant hazard.

Industries where noise is a prominent hazard include:

• Mining
• Construction
• Manufacturing
• Oil and Gas
• Transportation
• Military

These industries are some of Australia’s largest employers. In turn, a significant proportion of the Australian workforce faces serious health risks resulting from excessive noise exposure. High levels and durations of noise exposure can severely damage hearing in the short and long-term including conditions such as hearing loss, tinnitus, acoustic neuroma and vertigo. The risk of long-term harm due to noise exposure can be exacerbated by exposure to ototoxic chemicals which can damage the inner ear or auditory nerve pathways to the brain. These conditions can be chronic, requiring life-long management of the symptoms. Fortunately, hazardous noise exposure is highly preventable through risk management, monitoring and appropriate personal protection.

When are Workplace Sound Levels Hazardous?

Australian Work Health and Safety Regulations impose an obligation for PCBUs (persons conducting a business or undertaking) to do all they can to reduce the risk of noise-related injury in the workplace. State regulators also may impose different rules and obligations. For this reason, it is essential PCBUs are aware of the occupational health and safety regulations in their own jurisdictions.Under the WHS Regulations (and in accordance with AS/NZS 1269.1–2005) exposure levels should not exceed:

• LAeq,8h of 85 dB(A) – sound level pressure considering level and length of noise exposure period.
• LC,peak of 140 dB(C) – peak instantaneous sound level pressure during work period.

If these sound levels are exceeded, it is important for precautions to be taken to prevent noise-induced hearing loss. PCBUs may refer to the Model Code of Practice for Managing Noise and Preventing Hearing Loss at Work for guidance on how to meet their obligations to prevent excessive noise exposure under the WHS laws and regulations.

Conducting Noise and Sound Monitoring in the Workplace

To determine the extent of noise mitigation or hearing protection that is required in a workplace noise surveys should be undertaken to assess worksite sound levels and individual noise exposure. Occupational noise assessments can be done by an occupational hygienist or a competent person with skills and experience to adequately conduct noise assessment (AS/NZS 1269.1-2005).

Noise monitoring is generally conducted with sound level meters or noise dosimeters. Sound level meters, such as the SKC SoundCHEK Connect, are primarily used to quantify the overall loudness of sound in an environment. Sound level meters are available in two performance categories, class 1 and 2. The classes are defined by the International Standard IEC 61672-1:2002 based on electro-acoustical performance specifications. In contrast, noise dosimeters like SKC’s NoiseCHEK are small personal instruments worn on a worker’s shoulder that are used to measure an individual’s direct noise exposure throughout the workday. Both types of instruments may be used concurrently to comprehensively assess overall sound levels and noise exposure in the workplace.

Personal Hearing Protection for Occupational Noise Exposure

Where practicable, the first step in the hierarchy of risk controls to mitigate sound-related hazards should be to eliminate or reduce noise levels. In many industries, such as mining or construction, eliminating loud hazards like noisy machinery is not possible. In this case, the model Code of Practice for Managing Noise and Preventing Hearing Loss at Work suggests alternative noise reduction methods, including changing the way the work is done (achieving the same result with less noise) or isolation of the worker from the noise source.

If reducing noise levels in the workplace is not possible, personal hearing protection is essential to mitigate the impact of exposure and reduce the likelihood of adverse health effects. As well as the level of sound reduction, it is important for the hearing protection to be practical for the job. Factors such as the awareness of surroundings, concentration required for the task and other personal protective equipment which may be required to be worn along with hearing protection should be considered.

All personal hearing protection should comply with the following standards:

• AS/NZS 1270:2002 Acoustics – Hearing protectors: to ensure hearing protection is tested and approved in accordance with the Australian Standard.
• AS/NZS 1269.3:2005 Occupational noise management – hearing protector program: to ensure proper maintenance and selection of hearing protection.

There are a huge range of hearing protection options available such as over-ear earmuffs and disposable or moulded earplugs. In Australia, the most widely used methods for selecting hearing protection is the class system under AS/NZS 1270:2002 Acoustics – Hearing protectors. Under this classification method, hearing protectors are classed 1 to 5 depending on the eight-hour exposure level (L_Aeq,8h) the wearer experiences.

For example, if a worker is exposed to 103 dB(A) over a standard 8-hour shift, then a class 4 hearing protector should be used.

Implementing Hearing Protection Fit Testing

The effectiveness of hearing protection to reduce noise exposure may be significantly limited if the protection is poorly fitted. In states which have implemented the model WHS laws and regulations, there is an obligation for PCBUs to ensure PPE is a suitable size, fit and is reasonably comfortable for the worker who must use it.² To ensure PPE fits correctly, hearing protection fit testing is necessary. Fit testing affirms whether an individual’s personal hearing protection attains the level of noise reduction which is required under the regulations and to protect hearing health.

Hearing protection may be tested qualitatively or quantitatively. Qualitative fit testing involves a pass or fail assessment based on the ability of the individual to detect a certain volume and frequency through their hearing protection.

Quantitative hearing protection fit testing systems, such as the 3M E-A-Rfit Dual-Ear Validation System, measure an individual’s personal attenuation rating (PAR). PAR estimates the noise attenuation achieved by an individual whose hearing protection fit is being assessed. The PAR can be subtracted from the A-weighted sound pressure level (in dBA) to provide a predicted individual level of noise exposure. An advantage of objective hearing protection fit testing systems is that it tests a range of frequencies rapidly, and in the case of the 3M E-A-Rfit, test 5 frequencies in under 5 seconds per ear. Time-efficient testing allows more workers to be tested, more often.

The effectiveness of hearing protection is highly dependent on the individual’s ability to properly fit the equipment. By testing the fit of hearing protection, this also ensures that workers can attain a proper fit when donning the hearing protection themselves. Some hearing protection fit testing instruments, such as the 3M E-A-Rfit, include additional training features to ensure that workers can consistently don their hearing protection to achieve an optimal PAR.

Audiometric Testing

Audiometric testing is a fundamental aspect of determining whether hearing protection measures and fit testing programs are effective. Regular hearing tests are mandated in the WHS Regulations or workers frequently required to use PPE to protect them from hearing loss due to excessive noise exposure. Some states, such as Western Australia (WA) have implemented a grace period before the audiometric testing procedures required under the model WHS Regulations are enforced (WA WHS (Mines) Regulations).³ These provisions are set to commence on 31 March 2024.⁴ If workers are found to be suffering hearing loss, this may indicate that noise hazard control methods are not sufficiently mitigating noise exposure or improving worker aural health outcomes.

Due to the high incidence and harmful health effects of excessive occupational noise exposure, there is a significant range of controls which should be deployed to mitigate workplace noise. Elimination of noise, hearing protection (including fit testing), and audiometric testing are all necessary to ensure programs to protect worker hearing are effective and comprehensive.

Air-Met Scientific are distributors of the 3M E-A-Rfit Dual Ear Validation System as well as a wide range of noise and sound monitoring instruments including leading brands such as SKC Inc. and TSI Inc. Contact your local Air-Met Scientific today.

Footnotes

1. Productivity Burden of Occupational Noise-Induced Hearing Loss in Australia: A Life Table Modelling Study

2. Model Work Health and Safety Regulations - Safe Work Australia

3. Noise-Induced Hearing Loss - Workcover WA

4. Work Health and Safety (Mines) Regulations 2022