Workplace Noise Monitoring
Workplace Noise Assessment
Workplace noise monitoring is a necessary aspect of any Health and Safety strategy. If you are a Safety Professional operating in a noisy work environment and tasked with this responsibility, this may appear a complex undertaking at first. It is always worth remembering what you are trying to achieve in order to safeguard the hearing of your workers. This can be summarised as:
"Minimising or avoiding the risk of noise-induced hearing loss in the workplace to comply with local, noise-based, up-to-date legislation”
Such legislation is usually based on a European Directive that is then modified to suit the needs of each particular country. For example, in the United Kingdom, the ‘The Control of Noise at Work Regulations 2005’ are based on the European Union Directive 2003/10/EC; usually called “The physical agents (noise)” directive and expanded upon by the Health & Safety Executive. In April 2016, the Regulations will have been in place for 10 years.
The extent of noise-induced hearing loss
One in six of the British population suffers from hearing loss. Unfortunately, future projections do not look promising as it is estimated that, by the end of 2031, there will be 14.5 million people with hearing loss in the UK. Noise-induced hearing loss (NIHL) occurs when someone is continuously exposed to loud or persistent noise, whether when working or listening to loud music. According to the World Health Organisation, noise exposure is the main cause of permanent hearing damage in the workplace. It is also known as Industrial or Occupational Deafness. In the UK, research estimates that over 2 million people are exposed to noise levels at work that may be harmful. The Control of Noise at Work Regulations (2005) require employers to prevent or reduce risks to health and safety from exposure to noise at work. It is worth noting that employees have duties under the Regulations too. More information and guidance about employers' duties towards their employees to reduce the risk of noise exposure can be found by clicking on the link provided.
How to protect workers and meet the regulations?
The first action should be to obtain and read your national regulations and any advice leaflet. In the UK, both can be found in the HSE (Health and Safety Executive) booklet L108 ‘Controlling noise in the workplace'. This gives excellent and accurate advice in clearly marked sections. The data in the HSE booklet applies all over the European Union and is one of the best guides available in the English language.
Firstly, you need to establish if you do, or do not, have a noise problem in each of your main areas or work zones. There are a number of simple rules to determine this (click link here or see article below). However, to be absolutely safe, even if you are sure you do not have a noise problem, you would be advised to perform and document some simple noise measurements to provide long term evidence of your basic workplace noise assessment.
Employers who do not realise how serious industrial deafness is and who may have inadvertently ignored the regulations may be facing significant claims in future by employees for noise-induced hearing loss. It is worth noting that, in 2013, 60,000 claims notifications were recorded in the UK alone for noise-induced hearing loss (NIHL). This represents a significant increase since 2001.
There is no way of bringing back the hearing of workers affected but future claims can be avoided by limiting the exposure of noise to staff.
We have written many articles on the Regulations and workplace noise assessments, please consult Pulsar noise measurement blog for more information.
Limiting the exposure of noise to staff
A calibrated, easy to operate, noise or sound level meter such as the Pulsar Model 14, Model 82A Assessor or Models 41 & 42 from the Pulsar Nova range would be an ideal choice to simplify the task of performing a basic noise assessment of noise levels.
As a crude guide, if you are in an area where the noise is intrusive but normal conversation is possible, this would have a probable noise level of around 80dB(A). If people are working in this environment for 6 hours or more, you would need to carry out a formal noise risk assessment. If you need to shout at someone who is about 2m away and this noise level occurs for 2 or more hours per day, you need to carry out a formal noise risk assessment.
|Level in decibels ‘A’ frequency weighted||Actions required to meet the regulations|
|Areas always < 75dB||Brief risk assessment only – no other action|
|Areas between 75 & 85dB for a proportion of the time||Initial survey using an Leq meter or noise dosemeter|
|Areas where levels are likely to give an 8 hour exposure of 80dB(A) or more.||A full survey with clear identification of levels & corresponding actions; ideally with noise sources listed and personal exposure estimates for all workers likely to be at risk from noise induced hearing loss.|
Noise Risk Assessment survey – the basics
In Europe, once you have established that you have employees that are likely to receive an exposure of 80dB(A) or above, you need to carry out a formal workplace noise monitoring survey.
To start, you need to measure the noise levels and for this there are two equally acceptable methods. The first is by measuring noise levels using an integrating sound level meter and subsequently calculating exposure levels based on the duration of exposure to each noise source. The second uses a noise dosemeter, now better known as a Personal Sound Exposure Meter (PSEM) to measure the exposure to noise of each individual.
Pulsar Instruments Plc makes both types of instrumentation and leaves the decision to the user. Each noise assessment method has its advantages but you need to decide which method is best suited to your specific task. Should you need any help, please contact one of our technical team who will be pleased to offer you advice and guidance. Often a combination of approaches gives the best results. For this reason, Pulsar has introduced its bespoke “Safety Professionals kit”.
Sound Level Meter - the hand-held method
The guide requires an instrument that has the following minimum characteristics:
- ‘A’ frequency weighted Leq (time-average noise level)
- ‘C’ frequency weighted Peak around 140dB (LCpk)
- At least IEC 61672 Class 2 accuracy
Each sound level meter within our Assessor range has a special ‘ready reckoner exposure table’ which is displayed after each measurement to help you. It also provides a ‘settled’ indicator to help you decide when the average noise level has stabilised. Please note: the formal symbol for A-frequency-weighted Leq as defined in IEC 61672 is LAT, but the use of Leq has become accepted. The Pulsar Nova range such as the Model 43 or Model 44 sound level meter offers such functions and are recommended for occupational hygiene and industrial noise measurement.
Noise dosemeter or PSEM - the bodily worn method
If using a Personal Sound Exposure Meter (PSEM) or noise dosemeter, the setting-up is similar to that of a sound level meter. The batteries must be charged and the unit must be calibrated before the measurement. The PSEM is then fixed to the worker as near to the ear as convenient and measurement can begin. In the case of the Pulsar doseBadge, simply point the Reader unit, with its infra-red communication, at the badge and press the ‘Start’ button.
At the end of the working shift, the badge is stopped by pressing the ‘Stop’ button on the Reader unit. The doseBadge is then removed from the worker and the data in each badge is downloaded to the Reader where it is now available to inspect. The data can also be transferred onto a PC, using the Pulsar software programme (dBlink3) provided, allowing you to analyse efficiently and report on the measurement.
A key benefit of the Pulsar doseBadge system is that it gives the full time history of both ‘A’ weighted Leq and ‘C’ weighted Peak. This allows you to get a much clearer picture about real work patterns, rather than each worker's subjective “opinion” as to the levels.
Time history of a full working day using the Model 22 doseBadge and dBlink3 software
What do we need to measure?In the industry two different noise metrics are used to determine the risk from noise. The main one effectively represents the overall energy or the “amount” of noise and is described by LAeq and expressed as the continuous equivalent level (the average noise level), while the other represents the absolute highest pressure occurring, called the PEAK value, described by LCPeak or LZpk. Both the average value and the peak level are needed as whilst most hearing damage occurs as a result of noise exposure over a long period, a single very high value impulse can also cause damage. The ‘energy’ metric in Europe, is legally defined in terms of LEX,8h, the average level over an 8-hour daily period. In the UK this is still called the LEP,d (daily exposure level) but both are essentially the same thing. Officially LEX,8h or LEP,d is the Leq (or average level) normalised to an 8 hour working day. Different actions need to be taken at different levels, but from 2006, there has also been the introduction of the new 87dB(A) legal limit which was a major shift in policy.
Measures to be taken when the Exposure Value is 80dB(A) or above
- Identify all the employees affected.
- Inform all employees of the potential risk to hearing
- Publish results
- Fit signs recommending the use of Hearing Protection
- Provide a choice of appropriate hearing protectors on request
- Provide adequate education / training to meet these requirements.
Measures to be taken when the Exposure Level is 85dB(A) or above
- Areas concerned must be marked out and appropriate warning signs displayed.
- Personal Hearing protectors must be worn in these zones.
- An Audiometric Health Surveillance Programme must be established.
- The exposure of employees must be reduced as far as reasonably practicable.
- Noise should be controlled at source (Engineering solutions, Insulation, Absorbent Lining, Enclosures etc)
‘Exposure Limit Value’ Legal limit of 87dB(A) over 8 hours.
87dB(A) is the maximum permissible noise level exposure to actually impinge on the exposed person's ear (including the use of hearing protection).
Do I need to make any additional measurements?
Once you have determined that noisy areas are generating dangerous exposure levels to workers you need to initially prescribe hearing protection. You then need to carry out a measurement of ‘C’ weighted Leq and / or a 1:1 Octave Band Analysis.
|‘C’ weighted Leq||SNR method|
|‘C’ minus ‘A’ weighted Leq||HML method|
|1:1 Octave Band Analysis||Octave Band method|
Most hearing protection packages contain data for SNR, HML and Octave Band values. These can be used in conjunction with your measurements to prescribe suitable personal protection equipment (PPE) matched to your actual noise.
A Simple to use HSE Spreadsheet Style Calculator
A sound level meter which measures octaves exists in two forms, a REAL TIME ANALYSER or RTA, such as the Pulsar Nova where each octave is measured simultaneously, or the serial method where each octave is measured one at a time, such as with the Pulsar Assessor Model 84. From the 1:1 Octave Band data, it is possible to calculate results manually or it can be done automatically by using the excellent Pulsar Analyser software. The software contains a database of hearing protection, so that the level at the ear is automatically calculated by the software. Also check our latest Pulsar Nova Models 45 & 46 that offer real time 1:1 octave band filters as standard.
Most legislation requires you to ‘field calibrate’ your sound level meter or PSEM before and after each measurement session.
If it is correct both before and after the readings, you can assume it was correct during the measurement and the instrument, or more especially the microphone, has not been accidentally damaged. Pulsar Acoustic Calibrator Models 105 and 106 are the correct units for all of these sound level meters and they have formal, legal, European Pattern Approval. Many users are careless about such routine calibration, but it is essential for compliance with the legislation, so always note in the report that you have done this field calibration.
The Model 22 doseBadge system has an integral calibrator in the Reader unit, making calibration a straightforward task.
Note: In the older standards such as IEC 60651 and 60804, meters were classified as 'Type 1' and 'Type 2', but in the new standard IEC 61672, they are defined as Class 1 and Class 2.
Clearly, the best thing to do is to reduce the noise AT SOURCE, by screening machines, slowing them down, changing technology or any of the many ways available. In many situations, the ideal is not possible to achieve and the reality is that hearing protection will have to be used.
A full survey will include full details of all the noisy processes, in other words, mapping the various noise sources, determining the people exposed and the various levels; all obvious matters. The subsequent report should include immediate actions needed – such as introducing ear defenders - as well as longer term noise reduction strategies. It is clear that in any noisy space, the loudest noise measured must be used for everyone in the vicinity, unless a separate measurement is taken at each worker’s location. Such a separate measurement is easily done with a personal sound exposure meter (PSEM) such as the doseBadge noise dosemeter.
Who should measure?
In the UK, a ‘competent person’ should do it. One way to become a ‘competent person’ is to attend a short course, typically four days in length, under the auspices of the Institute of Acoustics. These are excellent and after a short examination, they offer formal certification.
Pulsar Instruments Plc offers a “One Day” noise awareness course, written and presented by members of the Institute of Acoustics that focuses on the basics of noise at work, current regulations, basic survey advice, noise control and the correct use of noise measurement equipment. In motoring terms, it is a course for drivers, not mechanics.