Major factors of industrial noise-induced hearing loss in Hong Kong.

A tripartite participation of government, trade unions and university was formed in 1988 to study the situation of industrial noise and hearing acuity of workers. Since 1982, the six industries identified by the Noise Control Office were construction, electronics, metals, plastics, shipbuilding and repairing, and textiles. Safety-subcommittees were formed. With the help of these subcommittees, 21 out of 32 medium-size factories responded to the study. A total of 922 sound measurements were made and 1062 out of 10724 workers were examined. More than one third (37.5%) of workers worked in locations with noise level in excess of L eq (8h) 90 dBA. Among examined subjects, 39.8% were exposed to L eq (8) 90 dBA and above and 18.6% were found to have industrial hearing loss. Multiple logistic regression analyses adjusted for sex and age showed that for hearing loss, the important risk factors were duration of occupational noise exposure, noise intensity, floor vibration and military experience. Current legislation and measures in hearing conservation were inadequate despite the implementation of inspection by the Noise Control Office. Recommendations were directed at amending relevant legislation, increasing supervision of use of personal ear protection, and strengthening health education and audiometric surveillance of exposed workers.