Noise induced hearing loss among textile workers of Taban factories in Yazd

Noise induced hearing loss is one of the most common occupational diseases in the world. It is thus introduced as one of the ten principle work-related diseases. According to the estimation of WHO, noise approximately causes a daily loss of 4 million US dollars throughout the world. This cross-sectional and analytical study was carried out on 100 workers of Taban textile factory in Yazd to assess hearing loss in the left and right ear of the staff at weaving, spinning and mechanical sections. This was done at 250, 500, 1000, 2000, 4000, and 8000 Hz frequency by means of audiometer. Besides, mean noise intensity in the auditory system of the workers (who had already been examined) was measured during their own shifts. The obtained data was statistically analysed by means of SPSS software and ANOVA; and LSD (less significant difference) was calculated. P≤0.05 was taken as the significant level. Mean age and work history were 38.9810-43 and 13.836.1 respectively. Findings indicated that noise induced hearing loss (NIHL) would be 0.18, if sound intensity increased one degree and work history were stable. But if sound intensity were stable, NIHL would be 0.37 when work history increased one degree. ANOVA statistical test (at the confidence level 95%) showed that the increase in NIHL is different in various occupational groups. Hearing loss was observed at different levels and at all frequencies in textile factory workers. However, hearing loss in the work begins at 4000 Hz and according to regression analysis the effect of work history on NIHL is more than the effect of sound.