A PILOT SURVEY OF NOISE AND HEARING ACUITY OF WORKERS ENGAGED IN SAWMILL OPERATIONS IN SOUTHEASTERN NIGERIA

Abstract

Noise measurements were carried out at seven workplaces in a Calabar based sawmill (Seromwood Industries Limited) to evaluate the noise situation in the factory, which employed 24 workers. The production line consisted of a Headrig, one Resaw, an Edger, a Frame Saw and a Circular Cross-cutting Saw. The ears of 14 workers who had been engaged in the sawmill for lengths of time ranging from 5 to 20 y with work schedules that exposed each to noise for 8 h daily were otoscopically and audiometrically examined. Sound level measurements and the subsequent calculated A-weighted Equivalent Noise Levels to which workers were exposed daily (dose) showed that the probability of hearing-loss occurring was high. Audiometric assessment of hearing acuity showed a lowering of hearing threshold in 71% of the workers sampled. This averaged 30 dB. Fifty per cent of the workers showed the classical steep dip (acoustic
notch) at 4000 Hz on both ears, characteristic of noise induced hearing loss and this was associated with the high noise levels workers in the various sawmill workplaces were exposed to daily. The percentage incidence of hearing impairment increased progressively with age.