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Improving worksite safety: assessing noise levels and conducting hearing tests at a refuse sorting centre proved an interesting challenge for an occupational health nurse in Northland.

For the past four years, I have been working as an occupational health nurse (OHN) in Northland. Part of my role last year was to help a small, privately-owned refuse sorting company meet its obligations under the Health and Safety in Employment (HSE) Act 1992, to protect its employees from occupational noise hazard and risk to their health.

My brief, at this small plastic and glass bottle recycling business, was to check environmental noise levels, set up health/wellness and hearing screening for baseline levels, and establish annual hearing monitoring.

This case study concentrates predominantly on the noise risk and hazard to hearing at the recycling centre, and how I established the hearing monitoring and surveillance programme. It also discusses some of the ethical issues I encountered.

The recycling centre is a stand-alone business on the west coast of Northland, operated as part of an adult special needs trust. It comprises a working dry-stock farming unit, full-time live-in accommodation, and various outbuildings designed to cater for the needs of intellectually disabled and special needs adults. These adults are, in turn, looked after by support staff employed by the trust. The trust is funded by the Ministry of Health and the refuse centre by a contract with the local district council. The adults living at the trust work both on the farm and at the refuse centre.

Environmental description

The frontline staff exposed to the noise hazard area are those with special needs (usually about 12-17 each shift) who generally work a three-to-four-hour shift, three days a week, on the recycling conveyer belt, before returning home to their accommodation.

At one end of the workshop, a forklift delivers crates of plastic and glass bottles, which are then emptied onto a seven-metre-long conveyer belt. As it travels along the conveyer belt, the material is separated into glass and plastic. The glass bottles are tossed into hand-held crates and then tipped into waist-high metal bins. These bins are located about one to two metres away from the conveyer belt.

The area is highly motorised and noisy, with regular peaks of "impulse noise" as the glass is tipped into the bins. The staff had been allocated class 4 grade earmuffs.

My role was to undertake a screening noise assessment of the refuse centre workshop area with a hand-held noise meter, note noise levels that fell outside standard guidelines and establish if any staff risked being affected by those levels. I was also to take histories of previous occupational noise exposure, do individual hearing tests, attempt to identify any historic hearing loss and report any issues pertinent to any occupational hearing loss.

In addition to the noise screening, I was asked to examine the working environment, and to identify any health-related physical risks and hazards possibly affecting both the special needs and the support staff.

I was also asked to conduct wellness checks for management and support staff. This involved offering finger-prick cholesterol and blood sugar screening, and blood pressure checks, as part of a company initiative to encourage wellness in the workplace.

At the end of the checks, I was to supply a report detailing decibel levels at the refuse centre, advise on appropriate hearing protection, and any other actions necessary to ensure the employees screened were not exposed to risk or hazard in their daily work.

Apart from two special needs employees who acted as truck runners outside the refuse centre, the other special needs employees were mostly assigned to working on the waist-high conveyer belt. Several were assigned to bottle disposal. They had to lift to chest height, then empty, recycle-sized bins into large metal skip bins. All workers wore protective gloves and hearing defender earmuffs supplied by the trust. The floor was concrete with no fatigue mats underfoot. There was a forklift operating near the workers, with no exclusion zone marked. Otherwise, the physical working environment, including the height of the conveyor belt, didn't seem to present any problems.

According to the noise-level screening, workshop noise appeared to be the greatest hazard to the employees. Initially, hearing protection appeared to be worn at a grade lower than appropriate, and no checking/screening process was in place to judge actual noise levels, or to monitor the efficacy of control measures. Under the HSE Act, a company is obliged to attend to this.

I conducted hearing tests on 12 support staff--the refuse centre manager, office/administration staff, rubbish truck drivers, workshop yardmen and groundsmen. I also checked for any musculoskeletal issues if their job had particular ergonomic issues. Support staff were also offered wellness checks.

Special needs employees

Seventeen special needs clients live at the trust and commute 40 km return, three days a week, to the refuse centre. The employees are both male and female. Some of them have Down syndrome, most with a mixture of mild to severe cognitive conditions and speech disorders. A small number of the adults tested had marked attention and learning deficit disorders, with several having extremely heightened anxiety and needing constant reinforcement during their appointments. To create a safe environment for both the client and the nurse, all testing was done with a support staff member present.

Different testing methods

To establish basline hearing, I used two differing methods, either pure tone audiometry using a calibrated GSI-18 audiometer as a preference or a standard clinic-based whisper test. My first task was to explain how the pure tone audiometry test was conducted. I kept explanations as simple as possible and, in the majority of cases, this was sufficient.

Where someone was unable to understand the pure tone audiometry test explanations, I used a basic whisper voice test to ascertain a basic level of hearing. (1) I used this method with five of the 17 clients. As I could only assess basic hearing ability, I did not include the results in my final report.

To perform the whisper test, the nurse instructs the client to try repeating a two-syllable word whispered in their ear. The client, or the carer, then blocks one ear by pushing on the client's tragus. The nurse stands on the opposite side, about 50cm away, then whispers a double-syllable word, eg "Wednesday", which the client should be able to repeat. The test is then repeated one metre away. If the client can successfully repeat the word with each ear blocked in turn, this is reported as "no apparent hearing deficit"; in other cases, as "an apparent deficit on either the right or left side".

I performed the hearing tests in both the refuse centre administration room and in the main lounge of the skills centre. Ambient background noise was acceptable, and clients who undertook pure tone audiometry were tested with GSI-18 hearing earphones to avoid the need for audiometry earplug/tips. I examined the employees' ear canals before testing. If the clients heard the beeps, they either tapped to indicate, or used words or some other vocal sound. I needed to monitor the clients constantly during the process to ensure they continued to concentrate on the signals.

Hearing impairments

Hearing loss is expected in adults with Down syndrome. The physical nature of the syndrome (particularly narrowed ear canals) results in excessively high levels of ongoing wax secretion. Additionally, narrowed and shorter eustachian tubes from birth are often related to a history of childhood ear infections. Down syndrome also affects a person's ability to hear high and lower frequencies of sound. (2)

Children with Down syndrome, by virtue of their unique physiology, suffer a range of middle ear problems that can be treated successfully, if they are taken for routine ear cleaning and examination from birth. However, grommet operations are unusual among special needs children, which affects their hearing as adults. Some ear, nose and throat surgeons are not enthusiastic about inserting grommets in children with Down syndrome because they feel they are extruded more quickly and continual replacement may scar the eardrum. Hearing aids are often recommended, instead of medical/surgical intervention.

I was not asked to provide medical checks for the special needs adults. These clients receive monthly, fully-funded medical checks at a local GP clinic.

Among the support staff, along with a high rate of general hearing loss, a number of notifiable hearing losses were recorded. The majority of these staff members were middle-aged or older, and most had had extensive and varied work histories of heavy industry, farming and using firearms. One support staff member had a cochlear implant and was not tested as he was under audio specialist care. Another had sustained a major head injury in a motor vehicle accident some years earlier, which had resulted in profound hearing loss. In my final report, I drew to management's attention the value of conducting pre-employment hearing checks.

Ethical issues

Undertaking these hearing and wellness checks has been a job that has really stood out for me as an OHN. Dealing with some of the clients presented a range of challenges and difficulties, but I enjoyed the job because of its uniqueness. This uniqueness also made me aware of a range of ethical issues.

Because of the intellectual disabilies and special needs of the clients, power differentials could have emerged. The clients' rights to fair access to health care raised the issues of how to gain informed consent, ensure client autonomy, promote beneficence and avoid paternalism. In addressing these and to ensure equity, it was important for all parties--the health professional, the special needs clients, the skills trust management and the support staff who were responsible for caring for the clients--to maintain a relaxed environment.

To ensure informed consent and autonomy, a client must understand the purpose of an examination, the right they have to make their own health decisions, and to determine whether to accept or refuse treatment. (3) Where possible, with the majority of the special needs clients, informed consent was sought, albeit sometimes with difficulty. A signed consent process was attempted and usually gained, occasionally with the signatures given as a "mark". At all times, every attempt was made to gain informed consent through informative and relaxed dialogue. On occasions, the client's caregiver/support person helped enhance the level of understanding between myself and the client.

To act in the client's best interests or the client's good, both the professional and client must establish what that is. This knowledge can only be gained through dialogue between the client and/or family and health professional that respects the client's autonomy and choice in treatment options. (3) The working environment at the recycling centre was noisy and hazardous for the clients. I had to establish whether supplied hearing protection was appropriate, thus ensuring their best interests were met.

Avoiding paternalism

Autonomy means clinicians must respect the patients' decisions about their own care. Beneficence means clinicians act for the good of their patients. Generally, there is always potential for tension between the principles of autonomy and beneficence, and I expected this tension to be a factor during the hearing tests.

Clinicians act paternalistically when they act on the beneficence principle to the exclusion of the autonomy principle. Essentially, the autonomy principle overshadows the beneficence principle. As a result, acting paternalistically (at least when it comes to competent patients) is ethically unacceptable. (4)

I knew I would encounter some difficulties conducting these hearing tests. Attention spans varied widely among the special needs clients, and the caregivers were employed to help where decision-making was part of the process. For me, the client's self-determination was of paramount importance.

Occupational hygiene

Before undertaking any noise survey within the workplace, it is important to understand what exactly needs to be measured.

My job initially was to set up baseline hearing levels for the workers. From the outset, it was also vital to determine the correct class of hearing protectors to be worn. To do so, it was first necessary to establish the average decibels the workers were exposed to and equate this to an appropriate protection level.

Occupational noise comes in two forms. The first is based on an average exposure over a working day. The second results from damage occurring to hearing from high levels of sudden impulsive or percussive noise, such as metal or glass dropped from a height onto a hard surface, or firearms going off.

Studies show that impulse noise carries a high risk of acute hearing loss, and can often have a more significant impact than constant lower exposures to industrial noise. One study showed that impulse noise produced permanent threshold shifts at 4000 and 6000 kilohertz after a shorter exposure duration than continuous steady background noise at the same levels. (5) Where exposure to impulse noise is cumulative, this can quickly become permanent and cause significant long-term hearing damage. (6)

Standards-based environmental noise measurement over a shift is done either using a sound level meter, or a personal dosimeter, and should be undertaken by a "competent person"--generally an occupational health and safety hygienist, specialist or OHN trained in noise measurement. (7) A sound level meter is primarily designed as a hand-held device, whereas the noise dosimeter is worn by an employee during their shift. I checked noise levels using a hand-held sound level meter. The checks were done at worker ear height, and within one metre of the noise source, thus meeting current environmental noise screening standards. (8)

Impulse noise levels occurred regularly at this worksite--every five to 10 minutes. In my final client report, I recommended that Class 5 personal protective equipment (PPE) was appropriate to protect against the higher impulse peaks. However, I also noted that, if the glass skip bins were moved outside the workshop, this could mean a lower grade of PPE was appropriate. The clients were currently wearing Class 4 PPE. If the bins were isolated geographically, then class 4 PPE would be appropriate, which would be cost effective.

Identifying hazards

Apart from the general noise risk, I noted and advised on two hazards in particular--having the forklift operation close to the workers and the position of the metal skip bins. I suggested the bins be moved to reduce the impulse noise hazard. This would then create a separate operational zone for the forklift. The company took up this recommendation. The wellness checks revealed several health issues with several of the support staff and these were reported on, with follow-ups and referrals undertaken over the subsequent weeks.

I am due to return to this workplace this month to conduct further hearing and wellness tests. It will be interesting to compare the results with last year, to see if the changes introduced have had any effects on clients' hearing.

Changing career direction

AFTER MANY years working in the printing industry, Steve Townsend found himself drawn increasingly to the world of health. Working as a volunteer ambulance driver finally clinched his decision.

"Nine years ago I enrolled in a nursing degree at Northland Polytechnic. I was the only male in a class of 70 women, but I found I loved the course and was even named the most outstanding student for my BN years."

After graduating in 2011, Townsend worked in accident and emergency for a while before finding his real calling as an occupational health nurse, working for a private company, StaffCare, based in Whangarei.

"I am one of five or six nurses working for this company," he said. "The work we do is mainly directed by the Health and Safety Act 1992."

Townsend's clients are largely men working in engineering and panel-beating businesses, the Marsden Point Oil Refinery, Golden Bay Cement in Whangarei, in timber mills and forests, and infrastructure groups like Firth, Downers, Fulton Hogan and Transfield. He is a certified vaccinator and workplace drug-tester, and also regularly undertakes pre-employment medicals, work-related musculoskeletal assessment, spirometry, audiometry, vision screening and phlebotomy.

"Working with men is quite uncomplicated. As a rule, they don't visit their GPs very often so this gives the job a very useful public health potential," he said. "I find I get on well with guys and I am getting good continuity with them, as I see them fairly regularly working for different industries in and around Northland. Being a male nurse gives me some advantage, I think. I only wish I had decided to go nursing years ago."

Report by co-editor Anne Manchester


(1) Jarvis, C. (2008) Physical examination and health assessment. (5th ed) St Louis, Missouri: Saunders, Elsevier.

(2) Sacks, B. & Wood, A. (2003) Hearing disorders in children with Down syndrome. Down Syndrome News and Update, www.down-syndrome. org/updates/222/?page=1. Retrieved 03/04/15.

(3) The Faculty of Occupational Medicine. (1999) Guidance on ethics for occupational physicians. (5th ed) London: Royal College of Physicians.

(4) Groll, D. (2014) Medical Paternalism--Part 2. Philosophy Compass,;jsessi onid=2E12D06700780888E387ECCCBDBCEE73.f04t02?deniedAccessCustomisedMessage=&userIsAuthenticated=false. Retrieved 03/04/15.

(5) Mantysalo, S. & Vuori, J. (194) Effects of impulse noise and continuous steady state noise on hearing. British Journal of Industrial Medicine. Retrieved 11/06/14.

(6) McBride, D. (2010) Guideline for diagnosing occupational noise-induced hearing loss. Otago University. groups/external_communications/documents/reference_tools/wpc091005.pdf. Retrieved 11/06/14.

(7) Department of Labour. (2011) Approved Code of Practice for the Management of Noise in the Workplace, Retrieved 23/12/11.

(8) Casella. (2014) Acoustics--Control of Noise at Work: Regulations, equipment and guidelines on use. Part 1: Basic quantities and assessment procedures, Retrieved 03/04/15.

Steve Townsend, RN, BN, PGCert (occhlth), works as an occupational health nurse with StaffCare in Whangarei.
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Title Annotation:case study
Author:Townsend, Steve
Publication:Kai Tiaki: Nursing New Zealand
Date:Jul 1, 2015
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