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PPE Certification for Hearing Protection

What are the legislative requirements that must me met in order to be able to offer PPE Hearing Protection in Europe? And, what regulations are in place to control noise in the workplace?

This article sets out to provide an explanation of the mandatory European Legislative requirements to offer PPE Hearing Protection.

It also sets out the Control of Noise Regulations relating to noise in the workplace, and the obligations of all employers and employees, including the provision and use of the appropriate PPE.

It is specific to the Hearing Protection category of PPE, and should be read in conjunction with the article on Product Testing and PPE CE Marking.

 

The Nature and Hazard of Sound

If an object falls on the head, or a particle gets in the eye then the result is immediate, and the hazard is easier to comprehend and therefore take appropriate action against.

Noise Induced Hearing Loss (NIHL) is slow, progressive, irreversible and permanent, the effects of which can take many year to become apparent.

It can also be avoided entirely with appropriate actions.

It is therefore vital that an appropriate action plan is implemented to deal with all workplace noises. Note that this also forms a sensible basis for dealing with domestic noise hazards.

Most other European Norms deal with hazard types which are either present or not. Noise hazard is more complex in that not only must the presence of the hazard be identified, but also the nature of the hazard.

Very few sounds consist of a single pure frequency. Nearly all sounds consist of a spectrum of frequencies, each of which has its own level of amplitude.

Sound amplitude levels are measured in decibels (dB), which relate to how the human ear hears sounds, so they are not a measure of energy or any other recognisable physical measure.

In most instances they are shown with an A scale weighting (dBA), which weights frequencies according to how the human ear detects them. This is most relevant for continuous noises.

If the noise is of an impact nature such as gunfire, then C weighting (dBC) is used, or sometimes the un-weighted scale, which closely follows the C scale.

When sound levels are measured they have to be measured not only on the basis of the noise level, but also on a range of frequencies. Having measured these specified frequencies it is important to understand that they cannot simply be added together to obtain the overall level of sound.

The dB scale is not linear, it is logarithmic, therefore the logarithm of the frequency dB level must be taken before adding together, then dividing by the number of frequencies measured, then the anti-logarithm taken to yield the overall noise level.

Another fact to demonstrate this non-linear nature is that doubling the noise level results in an increase of 3dB, so a 91dB noise is 4 times louder than an 85dB noise.

A very useful explanation can be found at http://www.noisehelp.com/decibel-scale.html.

Different HPD’s reduce (attenuate) sounds with their own “spectrum” of protection. It is therefore vital that the hearing protection selected will attenuate not only at the overall noise level, but also at the frequencies with highest amplitude (and thus constituting the maximum hazard).

 

Hearing Protection Legislation

The Control of Noise Regulations 2005 set out the Action Levels and Actions which must be implemented in order to comply.

Noise surveys should be carried out in all workplaces.

Employers are obligated to make a reliable and representative estimate of the noise levels to which their employees are exposed. If employees are exposed for longer than 8 hours then greater exposure results and higher protection is needed.

There are three Action Levels pertinent to the legislation.

 

Level Lower Upper Protected Maximum
Daily 8-Hour Exposure Level 80 dBA or 135 dBC 85 dBA or 137 dBC 87 dBA or 140 dBC
        Actions
  • A range of HPD’s must be made available to employees exposed to noise. Usage is voluntary.

 

  • Training must be provided on safe working, detecting hearing damage, risks of noise exposure, and correct use and fitting of HPD’s.

 

  • Audiometric screening must be made available to employees at risk of NIHL.

 

 

  • A range of HPD’s must be made available to employees exposed to noise. Usage is mandatory and must be enforced.

 

  • Noisy areas must be clearly identified and warning signs displayed.

 

  • Audiometric screening must be made available to exposed employees.

 

  • This level must not be exceeded, even when wearing HPD’s.

 

  • If exposure varies from day to day then weekly exposure levels should be used in place of daily exposure.

 

Action Plans

In order to comply with the regulations all employers should pursue the following steps for each employee work cycle.

  • Identify the Noise. This should be done via suitably qualified persons using calibrated sound meters at proscribed sample frequencies in line with noise measurement standard procedures. This can be achieved by training staff and providing meters with provision for calibration, or external experts can be brought in.
  • Produce realistic noise exposure estimates over an 8-hour day.
  • Seek to engineer out the source of the noise. If the source of the noise can be removed or reduced via means other than the use of PPE then this should be done as a first priority. Erection of barriers, or damping are examples of how this might be achieved.
  • Select and provide the correct HPD’s. This should be based upon the measured levels and the attenuation data provided by manufacturers (see Attenuation Performance Data below). Employees should be trained in correct use, maintenance and replacement of the HPD’s. The Employer must proactively enforce the use of HPD’s where relevant (see Action Levels above). Enforcement will be made easier by considering wearer comfort/preference, compatibility with other PPE (eg head, eye, respiratory) which may be required, the need to hear other hazards (eg fork lift trucks), the need to communicate with colleagues, and any medical disorders. Over-protection should be avoided, since vital safety sounds may be cut out altogether, thereby increasing risks.
  • Validate the protection provided by the HPD’s. Fit testing can be provided via electronic equipment to ensure that ear plugs are providing the required protection. This give a personal attenuation rating (PAR) for each employee. This is not mandatory however it does give reassurance that NIHL is not a risk. Note that individual physiognomy means that ear canals and hearing acuteness vary from person to person, therefore this provides a level of reassurance that is both important and worthwhile.

 

European Norms for HPD’s

The European Norms for Hearing Protection Devices (HPD’s) are:-

  • EN352-1 Ear Muffs – Headband or neckband
  • EN352-2 Ear Plugs
  • EN352-3 Ear Muffs – Helmet-Mounted

These set out the performance and marking requirements for all HPD’s.

 

Types of HPD

Ear plugs are the most basic and generally most effective form of HPD. They are often bright in colour so that they can be more easily seen when being worn, which helps with ensuring user uptake.

Human ear canals vary in size, shape and sensitivity. Accordingly it cannot be assumed that the published attenuation will be provided for all wearers. This is why fit testing is important in order to be absolutely certain that adequate protection is ensured.

Earplugs can often cause irritation to the wearer, and it should be noted that some plugs are offered in different sizes to compensate for larger or smaller ear canals.

This can help to reduce irritation and ease of fitting. Individually moulded permanent plugs are offered which should offer optimal fit and comfort. These are significantly more expensive but they constitute a one-off cost compared with disposable plugs.

If low attenuation is required then semi-aural plugs can be offered. These are mounted on a light band to ensure they remain in place, but do not intrude into the ear canal, they sit at the opening of the canal, and do not cause irritation to the same extent as some users experience with fully aural plugs.

Ear muffs are generally more comfortable to wear, but can interfere with other PPE, eg respirators, helmets, eyewear etc. A range of helmet-mounted earmuffs is available to overcome such interference, however compatibility with helmets should be ensured (see separate article on helmet compliance).

Note that different attenuation levels often result between headband and helmet-mounted muffs.

Ear muffs fall into two categories – passive and active. Passive muffs are cheaper in cost and provide reliable attenuation, however they attenuate uniformly and will cut out speech and other hazardous noises, which could increase risk levels.

Active electronic muffs are becoming increasingly popular in that they will cancel out the sounds within the environment, ie the attenuation depends on the noise levels.

They can also allow human speech or other types of sound to be heard. The cost of these devices has fallen over time as electronics have become more sophisticated and volumes have grown.

Just to confuse matters, a passive electronic muff is available which allows the wearer to open up to communication by pressing a button. Attenuation kicks in automatically again after a selected time limit.

In addition to providing noise attenuation, many muffs (both passive and active) are offered with built-in FM radio and/or connectivity with MP3 players. A further enhancement is the inclusion of radio communications.

 

Attenuation Performance Data

Each HPD carries a Single Number Rating which denotes the overall sound attenuation provided. This provides an indication of the potential suitability of the device for the required purpose.

If the SNR provides adequate reduction to below the legal limits then the frequency analysis measured should be compared with the frequency attenuation performance spectrum, which is shown on the packaging and data leaflet included with the device.

No individual frequency should be above the legal limits after attenuation has been deducted.

 

Markings

All HPD’s should carry the CE mark and the EN standard with which it complies (see above). Earplugs cannot show this on the devise, therefore it is shown on the primary packaging, usually a polymer sleeve. The SNR is also displayed on the packaging or within a leaflet.

 

Testing

All devices are tested in an environment of controlled sound levels and frequencies at a prescribed distance from the source of the sound. Devices are mounted on a dummy head (or within the ear canals of a dummy head), and measured outside the device and inside the ear canals where the inner ear is located. The difference between the two indicates the attenuation level. This is carried out at a range of frequencies as well with mixed frequency sound.

Testing is carried out during product development, prior to certification and against a proscribed sampling regime during manufacturing in order to ensure that performance is reliably maintained.

 

Registered Safety Supplier (RSS) Scheme

To help combat the problems of non-approved and counterfeit PPE, the BSIF has created the Registered Safety Supplier (RSS) Scheme. Companies displaying the scheme’s logo have signed a binding declaration that the safety equipment they offer meets the appropriate standards, fully complies with the PPE regulations and is appropriately CE marked.

 

Summary

For all Hearing protection applications EN 352 provides the performance standards and testing requirements to keep wearers protected by CE approved HPD’s in the workplace, backed up by testing requirements to ensure consistent manufacturing standards.

EN352-1 covers ear muffs, EN352-2 covers ear plugs, and EN352-3 covers helmet-mounted muffs.

This in no way removes the responsibility of the employer to ensure appropriate noise surveys, estimation of personal daily exposures, HPD selection, user uptake, provision of fitting, replacement, and cleaning/maintenance training, adequate storage, and of course replacement in the event of damage or wear when used in each application.

With an effective program NIHL can be eradicated from the workplace.

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