Assessing occupational exposure to noise
Today’s project was an assessment of occupational exposure to noise in a factory which specialises in the production of grain milling and grains sorting machinery. The main production building is divided into three separate areas. The offices and welfare facilities are situated at the front of the building, while the central part of the building is occupied by a testing facility and the rear is designated as the main production area. The production area is then subdivided into a sieve recovery section, sieve clearing section, grinding section, roll fluting section, turning section and an automated blasting section. During a typical working day employees are expected to be exposed to excessive noise for 7 hours and 30 minutes.
Calculating daily personal exposure levels
Using a B&K precision sound level meter, our surveyor was able to take measurements of A-weighted sound pressure levels and C-weighted peak sound pressure levels at the employees’ ear position while carrying out typical work operations. We were then able to calculate the daily personal exposure from the measured noise and the time the employee is likely to be exposed to the noise. We can then use this in order to confidently form an action plan to minimise the risk of exposure to excessive noise.
Results of noise exposure assessment
Our assessment of occupational exposure to noise revealed that the employees working in the colour sorting, sieve recovery and the grinding areas are likely to be exposed to a daily or weekly personal noise exposure level at or above the Lower action value of 80 dB. Whereas the employees working in the sieve cleaning, turning and roll fluting areas are likely to be exposed to a daily or weekly personal noise exposure level below the Lower action value of 80 dB. In all of these areas the peak exposure was not exceeded.
Therefore all employees will not be exposed to daily or weekly personal noise exposure levels at the exposure limit value of 87 dB or the peak sound pressure level of 140 dB especially while using the hearing protection already provided.
How to minimise exposure to noise
In order to comply with The Control of Noise at Work Regulations 2005 it is recommended that a noise assessment should be reviewed and updated when circumstances change in the workplace which could alter the level of exposure. Where there have been no changes, the risk assessment should be reviewed every two years. If new equipment is installed we recommend our client to employ a low noise purchase policy in order to minimise the noise level.
It is the employers responsibility to implement the use of hearing protection, he must ensure that employees are wearing the correct hearing protection when appropriate. All noise control equipment must be properly maintained and regularly checked to ensure that they are effective.
Employers also have the duty to inform and train all their employees about the dangers of exposure to excessive noise and how to minimise it by using the appropriate hearing protection provided. This training should be refreshed on a regular basis.