Recently we were asked to carry out an assessment of occupational exposure to noise at a manufacturing plant. It was our job to evaluate the daily personal exposure levels of employees to peak high intensity sound, and to identify sources of excessive noise and recommend suitable control measures. After completing our investigation we identified that noise exposure did not exceed regulations but we recommended that an audiometric health surveillance program be maintained.
The manufacturing plant was located near Great Yarmouth, and responsible for the fabrication of industrial firefighting equipment. The site consisted of an office, administrative section, open plan fabrication floor and mixed warehouse. The main fabrication building consisted of a machines shop, paint shop, fabrication shop and numerous other specialist facilities. Overall, there were around 50 employees working in the factory.
Workplace Noise Assessment Methodology
In order to conduct an enquiry into the workplace noise exposure, we needed to take detailed measurements. We took measurements using a precision sound analyser, B&K precision sound level meter type 2236. The sound level meter was then calibrated before and after measurements at 94dB and 1KHz. Next, we took measurements of sound pressure levels at the employee’s ear position whilst they were carrying out typical work operations. The employees daily personal exposure was then calculated from the measured noise and the estimated length of exposure.
Results of Noise Exposure Investigation
Our results indicated that employees working in the Test Area, Halo Line and Valve Assembly were likely to be exposed to a “Daily or weekly personal noise exposure level at or above the Lower Action value of 80 dB”. Whilst this was not a cause for major concern, we made additional recommendations to help the owners to ensure that noise exposure did not become an issue in the future.
Our Noise Exposure Recommendations
After conducting our investigation, our primary recommendation was that the plant aim to eliminate the risk from exposure to noise at the source or, where this is not possible, reduce the noise to as low a level as is reasonably possible (By means other than hearing protection). We also recommended that hearing protection should only be used when there is a need to provide additional protection beyond what has been achieved through noise control measures.
In addition, we recommended that the owners take an active role in ensuring that all noise control equipment and hearing protection is properly maintained. The introduction of initial audiometric testing at the start of employment, routine audiometric testing/health surveillance and exit audiometric testing at the termination of employment would do well to support employees working in production areas. Finally, to comply with current Noise Regulations, employers have a duty to inform and train any employees who are exposed to noise at or above the Lower Action Value of 80dB about the danger from exposure to excessive noise. Every employee should be provided with information which covers exposure levels and the risks that comes with high noise levels.