Noise and occupational health and safety

When a daily exposure to noise of 85 dB(A) is exceeded plans must be made, and executed, to reduced the exposure, beginning with reduction at the source. Devices for hearing protection should only be used as temporary measure, or as a last resort.
From a daily exposure level of 80 dB(A) appropriate and individual hearing protection must be available. The worker is obliged to use the hearing protection if the daily exposure level exceeds 85 dB(A).
Under no circumstance a daily exposure level of 87 dB(A) may be exceeded. For this exposure limit level of 87 dB(A) the effect of hearing protection may be taken into account.

The noise at workplaces must be examined if it is likely that the average level exceeds 80 dB(A). The international standard ISO 6912 describes the way to investigate the daily exposure to noise in workplaces. ISO 6912 must now be accepted in all EU, and associated, countries. Thus in all EU countries noise at the workplace should be determined in a similar way.
At large plants with few workers it is common to make noise maps instead. Full text of the EU directive

Effects of noise

Excessive noise harms the hearing. The hearing organs are microscopic precision instruments which can, in cooperation with the hyper-processor called our brains, discriminate and analyse complex signals. Hearing damage caused by noise is irreversible and has adverse effect on our ability to communicate and enjoy life. But communication problems caused by damaged ears can cause problems at work too, and even lead to safety risks.
Noise levels which not directly threaten our ears can, and frequently do harm our performance: moderate noise levels can decrease concentration and communication and in the end the quality of the product or service.

A quiet working environment is not a luxury, its a quality.

Excessive noise not only affects the health of the employees, it also affects their attitude and their performance. In this way high noise levels are relevant to the quality of the product. This knowledge may change your ideas about the costs of noise reduction.
EU portal on noise at work