ABSTRACT
Occupational noise-induced hearing loss [NIHL] is an important yet often overlooked illness that can affect an individual's performance and safety at work. This study was conducted on twenty male workers exposed to both noise and vibration hazards generated from metal grinding and wood sanding in one of the military factories in Helwan. The average daily noise intensity was 105 +/- 7.9 dB. The examined group was all males with age ranging from 28 - 58 years with a mean duration of exposure of 10.75 +/-3.62 years. The workers were evaluated using a self- administered questionnaire, a medical examination including an ear examination, audiological assessment, and serum cortisol as a bioindicator for stress. Reassessment was done after one year from implementation of a noise damping procedure by shifting the workers to a new building opened from the sides and reducing the impact noise transmission by floating floors. So, the average noise level decreased to 80.6 +/- 4.0 dB. The study showed that maxim ii diminution of hearing was observed in the high tones more than 2000 Hz], with significant improvement in hearing threshold after establishing the engineering control, The improvement is more significant at higher frequencies, 4 kHz and higher. The mean level of plasma cortisol was 24.6 +/- 7.15 microg%, then decreased to 13.0 +/- 3.81 microg% after the engineering control with a difference of about 11.6 microg%. Both systolic and diastolic blood pressures were higher among the examined group and were markedly decreased after implementation of the engineering program and medical treatment with a mean difference of about 41.5 mmHg in systolic and 17 mmHg in diastolic blood pressure. Also, 75% of the workers reduced their dose of the treatment after implementation of the HCP but still most of them are controlled by medication. It is recommended that engineering control should be the first order of protection from excessive noise exposure. Physicians should become aware about the medical consequences of excessive noise, support legislation to reduce the problem and promote program aiming at noise control and prevention of hearing loss aiming at improving psychosocial stresses and increasing the performance capacity