[Noise as a stress factor for the onset of hearing disorders in workers using drilling equipment]

Noise is one of the commonest environmental pollutants and it is defined as a sound which bothers, irritates, which is unpleasant and can damage hearing. The degree of negative effects of noise depends on its intensity, spectrum of frequency, nature, duration of exposition and individual sensibility.

This work is supposed to establish the degree of correlation between hearing damage and professional exposition to one of physical stressors of work environment--noise.

Investigation regarding work conditions included intensity and frequency analysis of noise at workplaces. The examination sample included 101 workers of "NIS--Naftagas" section "Hidrosonda" employed as drilling workers. The control group consisted of 50 workers not exposed to noise or any other professional influences, like workers from the examination sample.

The results on the observed workplaces show that noise is of high intensity and bad frequency spectrum. Exposition of workers to noise is a highly important factor for hearing damages (p = 0.002). The relative risk for hearing damage is four times greater in relation to the control group (odds ratio 4.1). Attributable fraction (preventive potential) of noise factor is 61%. Smoking associated with exposition to noise multiplies the risk of hearing damage (odds ratio 5.8) while with non-smokers the risk decreases (odds ratio 3.0).

Professional hearing disorders occur slowly and increase with time spent at noisy workplaces. At the beginning it presents with buzzing in ears and dizziness followed by latent phase after which hearing disorders occur. Tone audiometry is used to register first signs of hearing loss, whereas manifestations in social contacts come later.

Once diagnosed hearing disorders cannot be cured so a lot more care should be paid to this problem. It is necessary to provide adequate work conditions by applying appropriate technologies, tools, work organisation, personal protection equipment, as well as previous and periodical examinations of hearing by tone audiometry before employing workers and during their work in noisy conditions.