Stop that Noise

Undesired, unpleasant and loud are all ways that the Oxford English Dictionary describes noise. When it comes to your workplace, noise can also be damaging for workers and lead to devastating consequences.

Due to their occupations, some workers can’t sleep because of the ringing in their ears, simply on account of the kind of work that they do. We have the right to finish our day’s work in the same physical and mental state as we started it in. Ill health should not be the result of poorly controlled noise levels in the workplace.

Background

Noises within the workplace can not only cause hearing problems, but can also affect your performance at work, including being able to read effectively, attentiveness, problem solving skills and memory. Who would have thought that a noise can prevent you from remembering simple work tasks?

Noise can also be the cause of accidents due to reduced signal recognition, limited auditory localisation and speech communication, misunderstanding of oral instructions, and masking the sounds of approaching danger or warnings.

Unfortunately, noise is a well known hazard within the workplace around the world and in all industries, whether you work in manufacturing, construction, leisure, entertainment or administration.

On average, 20 percent of the workers in Europe1 are exposed to preventable loud noises within their workplaces. Around 30 million people in the United States are occupationally exposed to hazardous noise. Since 2004, the USA Bureau of Labor Statistics has reported that nearly 125,000 workers have suffered significant permanent hearing loss.

Working and living in Europe is changing at an ever increasing speed. Based on the population growth between 2012 and 2013, the population of Europe in 2013 and the population of Europe in 2014, the total is estimated to be around 741.2 million people. This makes Europe the third most populous continent behind Asia and Africa.

A growing proportion of workers in Europe are employed within the service sectors; for example, construction, manufacturing or agriculture. With this growth, new risk areas evolve and can have implications for workplaces themselves, and also for the occupational safety and health system. Noise induced hearing loss is a well known hazard.

The European Agency for Safety and Health at Work said that workers who report high exposure to noise also report higher rates of hearing problems. There are significant differences within the sectors. Mining and manufacturing, construction and transport and communication report hearing problems more often than other sectors.

In other parts of the world measurements during the manufacture of textiles in Nigeria have recorded noise levels in excess of 130dB (A) which is equivalent to a marching band of 200 members, or the sound of a machine gun.

The results of an audiogram in a study of employees at an airport in China revealed a 41 percent prevalence in high frequency hearing loss in all workers. In the European Union, 28 percent of workers surveyed reported that at least a quarter of the time they were exposed to noise – loud enough to have to raise their voices to hold a conversation. This in itself is infuriating and can cause stress too.

According to national statistical data, noise is the main risk factor in Polish working environments. For years, the number of workers exposed to noise was greater than the number of workers exposed to other risk factors such as dust, chemical substances or vibrations.

According to European and national sources you are at a higher risk if you have a full time, non permanent contract or are a younger worker, as you are more likely to be affected by loud noises. They suggest that these two groups of people receive less information regarding health and safety issues, less training and less formal supervision and control in the workplace. This should not be happening within your workplace and employers should be encouraged to ensure everyone has the same information, training and supervision.

The Health and Safety at Work Etc Act 1974 places a duty on employers within the UK to their employees to provide information, instruction, training and supervision – this includes everyone who is working at their business.

What’s all the noise about?

Sound is a form of energy. This energy is transmitted through the air as pressure waves. The ear then detects these pressure waves and they are perceived as a sound, or noise.

When sound waves enter the outer ear, the vibrations impact the ear drum and are transmitted to the middle and inner ears. The middle ear has three small bones inside and they amplify and transmit the vibrations generated by the sound to the inner ear.

The inner ear contains a snail like structure called the cochlea, which is filled with fluid and lined with tiny hairs. These hairs are microscopic and move with the vibrations, and convert the sound waves into nerve impulses. The result is that the sound is heard.

Constant exposure to loud noise can destroy these hair cells, which will then cause hearing loss. The hair cells will not grow back and hearing will not be restored, leaving permanent hearing loss.

A decibel is a logarithmic measure of the ratio between numbers and is measured on a logarithmic scale, which means that small changes in the number of decibels results in a huge change in the amount of noise, and the potential damage to a person’s hearing.

The loudness of the noise is measured in units of sound pressure levels. These are known as decibels and are abbreviated to dB. A-weighting is a measurement scale that approximates the ‘loudness’of tones, and is normally used to evaluate environmental noise. This is measured as dB (A).

The technical angles

There are many terms within health and safety, such as directives, regulations, legislations, codes of practise and standards. These all mean and do different things, but must be abided by as they make up the laws that people follow in their working lives.

A directive is binding in its entirety and obliges member states to transpose it into national law within set deadlines. A directive enters into force once it is published in the official journal of the EU.

The directive that has been set for noise at work in Europe is the 1986 EEC Directive of Occupational Noise Exposure. This exists to provide protection to all workers from harm caused by exposure to noise. It was originally the 1986 EE Directive, which was altered in 2002 as it was decided by the European Union that a new directive would be released covering the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents like vibration.

A second step was also considered to ensure that the new directive covered measures to protect workers’ hearing. This not only addressed individual workers, but sought to create a minimum basis of protection for all community workers. There are also requirements within the Machinery Directive and the Outdoor Machinery Directive which make it clear that prevention through design is important in dealing with occupational noise.

In addition to the above directives, one of the most used global standards is the ISO 1999:2013 Acoustics – Estimation of Noise Induced Hearing Loss. ISO is a standard, a document that provides requirements, specifications, guidelines or characteristics that can be used consistently to ensure that materials, products, processes and services are fit for their purpose.

There are more than 19,500 published standards. The specific standard ISO 1999:2003 specifies a method for calculating the expected noise induced permanent threshold shift in the hearing threshold levels of adult populations due to various levels and durations of noise exposure.

Threshold shift is an increase in the hearing threshold – the sound level below which a person’s ear is able to detect any sound – for a particular sound frequency. The hearing sensitivity decreases and it becomes harder for the listener to detect soft sounds. These threshold shifts can be permanent or temporary.

The standard provides the basis for calculating hearing disability according to various formulae, when the hearing threshold levels at commonly measured audiometric frequencies or combinations of such frequencies exceed a certain value. The measure of exposure to noise for a population at risk is the noise exposure level normalised over an eight hour working day, LEX, 8h for a given number of years of exposure. It is applied to noise at frequencies less than approximately 10 kHz which is steady, intermittent, fluctuating, and irregular.

A further Directive 2003/10/ED, was published on February 6, 2003, and outlines the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents, or noise. The Directive sets exposure limit values and exposure action levels in respect of the daily noise exposure and peak sound pressure.

This Directive sets these limits at: • Exposure limit values: LEX, 8h=87dB (A) and peak = 200 Pa (1) respectively • Upper exposure action values: LEX, 8h 85 dB (A) and peak = 140 Pa (2) respectively • Lower exposure action values: LEX, 8h=80dB (A) and peak = 112 Pa (3) respectively

These above levels differ across the world. In China, for example, the eight hour average A-weighted sound pressure level is 70-90 and the upper limit for peak sound pressure is 155dB. This is very high and is equivalent to a fire cracker going off, or the loudest speakers in the world. The levels are too high and have a high risk of causing ill health in workers. Ear protection alone would not reduce the noise enough for it to be low risk.

The European Agency for Safety and Health at Work also recorded that in 2001, about 35 percent of workers in new Member States were exposed to noise at work for more than a quarter of their working time. About 15 percent of workers in the new Member States were exposed to noise so loud that they had to raise their voice to talk to people all the time, or almost all the time, and a further 19.4 percent of workers were exposed to noise from a quarter to three quarters of their working time.

In India, the eight hour average A-weighted sound pressure level is 90, and the upper limit for peak sound pressure is 140dB. In the United States, however, about nine million workers are exposed to time-weighted average sound levels of 85dB (A) and above.

Noise prevention

Noise levels in food and drink manufacturing can be between 80-100 dB (A) according to the European Agency for Safety and Health at Work. A study carried out within a food processing factory monitored numerous activities.

Jars were being removed by hand onto cardboard covered sheets before being transported by a conveyor to the filling line – this was via a narrow passageway. In addition to being subjected to physical and postural stresses likely to lead to work related musculoskeletal disorders, the employees at the factory were being exposed to loud noise levels. This was due to the impact noise from the jars. By enclosing a part of the process, noise exposures were reduced from 89 to 77 dB (A) which then gained 12 dB (A) at the workstation.

The Health and Safety Executive (HSE) in the UK carried out studies within various industries, including agriculture. A hammer mill used for the preparation of animal feeds was producing 93 dB at 1.2m. To reduce the noise exposure limits, an enclosure was constructed. It was a frame built from wooden battens and was self standing, which allowed for air vents to minimise noise seepage. Due to this enclosure the noise levels were reduced by 8 dB and the full cost of the solution was £80.00.

A company called Prevent, in Sweden, aims to improve the work environment, but had an issue communicating information and good practise with regard to mitigating against noise hazards. To help them get the message across they decided on a CD entitled ‘Sound and Noise’. This was launched to provide information and training to companies in Sweden and aimed at a wide range of target groups across a broad spectrum of workplaces. They found that this was an effective way to ensure that material was given out within workplaces to provide information on noise at work.

In 2005, a campaign was launched by the European Agency for Safety and Health at Work for the European Safety week. This campaign, called ‘stop that noise’, was launched to raise awareness of noise at work and the risks that it entails. It also aimed to show that noise is not just a hazard within the heavy fabrication industries, but within a wide range of sectors.

What can happen to you?

There are many health problems that can develop due to noise at work. Acoustic trauma or acoustic shock is caused by short bursts of extremely loud noises. This is an issue of concern in call centres when the volume on the telephone is set too high. It can result in sudden hearing damage and over time will cause more permanent damage.

In Europe, 22.5 million individuals suffer from hearing impairment, with 2 million being profoundly deaf. All together, in Europe the financial cost of hearing impairment has been estimated at EUR 78 billion per year, based on an average of EUR 3,500 per patient on annual costs for special education, speech therapy, hearing aids, physician and specialists’ fees, plus other expenses.

This is more than the combined economic costs of epilepsy, multiple sclerosis, spinal injury, stroke and Parkinson’s disease. Furthermore, this figure is likely to grow in time due to noise pollution and ageing. Hearing loss is the third most common chronic disability following arthritis and hypertension.

Tinnitus is caused by exposure to excessive noise, which can be caused by using machinery including chain saws, or even from music at a concert if you are working in the entertainment sector. This condition is a constant ringing and buzzing in your ears and occurs when the hairs within the ears are destroyed due to loud noise over long periods of time. Once the hairs within the ears are destroyed they will not be repaired, causing a lifetime of unpleasant constant noises in the ears.

Temporary hearing loss is known as a temporary threshold shift, which may occur immediately after exposure to a high level of noise. This could be recovered after spending time in a quiet place. Over time, this will result in permanent hearing damage.

There is also evidence of several non-auditory health effects associated with medium levels of noise. This includes voice problems, stress, cardiovascular diseases and neurological issues. Noise below the levels usually associated with hearing damage can cause regular and predictable changes in the body. Even ‘ear safe’ sound levels can lead to these health effects if they chronically interfere with recreational activities such as sleep and relaxation; if they disturb communication and speech intelligibility; or if they interfere with mental tasks that require a high degree of attention and concentration.

What can employers do?

Due to the high risk nature of noise, employers are required to control risks at the source of noise and eliminate or reduce them. Personal hearing protection is not to be used as the only source of protection – prevention control measures must be in place to control or reduce the risk of noise.

The use of controls within the workplace should aim to reduce the hazardous exposures, so the risk to loss of hearing is eliminated or reduced. Noise can be controlled with engineering controls – these are methods to isolate the noise source, which could involve the redesign of or modification to plant, equipment, and ventilation systems.

Administration controls can alter the way work is done including the timing of work, policies and other rules. By putting policies and procedures in place you will ensure there are rules to follow within the workplace, and ensure all employees are aware of them. This could be done in the form of training.

By increasing the distance between the source of noise and the workers, noise exposure will be reduced. Hearing protection devices such as ear muffs and plugs are an acceptable but less favoured option, and are only used when engineering and administrative controls cannot be provided, or are an addition to the controls.

All hearing protection should come with a SNR, or single number rating. This number provides the simple estimate of protection and it will give the wearer an approximate protection of 38 dB.

Protection will only be provided if the PPE is working correctly, so provide training to employees on how and when to wear protection to ensure it is effective.

Hearing protection may be used for people who are already suffering with hearing damage but is not the only source of protection against noise. Procedures could also be implemented within the workplace to reduce or illuminate the hazards, including health surveillance and regular noise assessments.

The general principles of prevention when controlling noise at work are to avoid the risks, evaluate the risks that cannot be avoided, combat the risks at source, adapt the work to the individual, adapt to technical progress, and replace the hazardous with the non hazardous.

Noise at work is a high hazard in most industries and is still causing employees and workers all over the world to suffer from ill health. The noise levels would be healthier if they were consistent all over the world to ensure that all employees received the same amount of protection.

Continued work needs to be done to ensure the control of noise is carried out within workplaces globally, and employers are encouraged to ensure that noise reduction measures are carried out within their business.

Published: 22nd Jul 2014 in Health and Safety International