Plant & Works Engineering
Keeping noise under control
Published:  08 April, 2021

Noise in the workplace poses significant risks to people’s hearing. Without the right tools and equipment to understand noise levels in your workplace, you could be leaving employees open to suffering from hearing loss. PWE’s Andy Pye reports.

Regardless of the industry or sector, every employer is bound by health and safety legislation and regulations. The Control of Noise at Work Regulations 2005 set out the measures that employers must follow to protect their workforce from the dangers excessive noise levels present and are legally enforceable.

The level at which hearing protection is required by law is 85dB(A) - the same noise level as a petrol-powered lawnmower. At this level, you only have eight hours of exposure before permanent damage is done to your hearing. Those who work in the emergency services are potentially exposed to 120db(A) when sirens are sounding; here the maximum exposure time is only nine seconds.

Sound-level meters

The legislation also dictates that for noise measurements to be legally compliant, the instruments you use must meet a minimum standard. UK legislation dictates that manufacturers must make sound level meters to meet IEC 61672 and that any microphone used for occupational noise measurements must be, at a minimum, Class 2. Many of the cheaper options available from the Internet will not be anywhere near meeting these standards, and mobile phone applications certainly won’t. The investment in the right equipment will ensure that the data is accurate, reliable and will stand up to scrutiny in any litigation should an employee make a complaint.

Field and factory calibration

The Control of Noise at Work Regulations 2005 state that for your data to be considered accurate and reliable, the instrument must be “field calibrated” before and after each measurement and “factory calibrated” at least every two years. Field calibration ensures that an instrument accounts for any minor fluctuations in the microphone that happen naturally or could have been caused by little knocks and bumps that occur as part of everyday use. Factory calibration puts every feature and function of the equipment to the test against incredibly high standards, ensuring that any significant discrepancies are eradicated, ensuring your instruments’ accuracy and reliability. Cirrus Research offers two levels of factory calibration: standard-traceable and UKAS-accredited (lab number 10148). Instruments from every manufacturer may be calibrated.

Hearing protection

Providing hearing protection seems a simplest approach – many employers often attribute the success of their health and safety programmes to distributing hearing protection. But according to the Control of Noise at Work Regulations 2005 this should be the last resort. The Regulations state that if, after having explored and carried out all the technical and organisational ways to reduce noise in the workplace, you identify that employees will still be exposed to noise levels at or above the Lower Action Value (LAV) of 80 dB(A), then and only then will you need to provide them with access to hearing protection (or issue it directly to those employees still at or above the Upper Action Value (UAV) of 85dB(A).

Many employers offer inadequate hearing defenders, either under-protecting staff or overprotecting them. It may seem as though it is difficult to have too much protection. However, with heavy machinery, over-protection could mean that they cannot hear safety alarms or their colleagues attracting their attention to potential danger. As a result, hearing protection should always be the last resort; the priority is to reduce the noise levels.

Hearing protection zones

Suppose a noise assessment finds several areas where employees are likely to be exposed to levels of noise at or above the Upper Action Value (UAV) of 85dB(A). The Guidance given in Regulation 7 of the Regulations suggests that hearing protection zones offer a way for employers to effectively manage the use of hearing protection, and states: “85 Making the use of hearing protection compulsory for workers exposed below the upper exposure action values (below 85 dB(A)) should be avoided, except within hearing protection zones.”

“86 Where workers are exposed to above the UAV and are therefore required to wear hearing protection, you should not necessarily make it compulsory at all times throughout the working day, (eg in areas or at times when noise levels are low). Hearing protection should be targeted at particular noisy jobs and activities and be selected to reduce exposure at least to below the UAV.”

These zones can serve as a reminder to any employees exposed to an LEP,d (daily personal noise exposure) at or above the UAV, for whom hearing protection is compulsory during particular jobs or activities, that they have a responsibility themselves to wear the hearing protection provided.

Noise-activated signage

Wearing ear defenders is not always popular with staff exposed to industrial noise, and it may not be practical for employees to wear hearing protection constantly, especially where the noise levels are intermittent or vary significantly over the day. Putting up a standard printed “Hearing Protection Must Be Worn” sign means that employees must follow it continuously in these zones and someone has to monitor the people to make sure they comply with the instruction.

Noise-activated warning signs, such as those supplied by Pulsar Instruments, provide an alternative temporary warning linked to the actual level of noise itself and can, therefore, help to manage the wearing of PPE. The way such signs work is that the employer sets a trigger level of say 80 dB(A); once noise reaches that level the sign will light up its warning. Such signs therefore effectively allow a designated area where “Hearing Protection Mandatory Only When Lit”.

These interactive noise warning signs offer the advantage then, that hearing protection need only be worn when necessary. Using hearing protection only when levels require means companies placing less reliance on using PPE as a noise control measure, more comfort for workers and less work-place isolation.

Such signs can also be used to mark out a factory into multiple zones. They can serve as an important safety function in work environments that rely on processes that involve or produce exceptionally loud sounds. Some signs can log and store noise levels and therefore give an indication of noise levels over time. Enabling the Employer to keep track of problem areas and investigate issues to prevent high levels of noise exposure in workers.

This article acknowledges information supplied by Cirrus Research and Pulsar Instruments

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