Investigation of noise hazards and hearing status of workers in outdoor quarries

Abstract

To investigate the noise hazards in open quarries and to provide a basis for further control of noise hazards. An investigation was performed during 2010 to 2011 among all open quarries in Deqing County of Zhejiang Province, China. The investigation included basic information of the quarries, the occupational health situation and noise intensity at the workplace, and the hearing loss of workers exposed to noise in quarry enterprises. The hearing test results were evaluated based on the Diagnostic criteria of occupational noise-induced hearing loss (GBZ 49-2007). A total of 25 enterprises with open quarries were investigated, of which only 30.4% (17/56) workplaces met the national standard. The median noise level was 92.5 dB (A). Fifty-four (10.6%) out of 508 workers in the 25 enterprises were diagnosed with binaural hearing loss in the initial physical examination, with 18.3% (93/508) under surveillance. The rate of normal hearing among crushing workers, mechanists, drilling workers, and blasting workers ranged between 27.6% and 41.4%, which was significantly lower than that among workers exposed to slight noise hazards (80.0%) or other workers (63.7%) (P < 0.05). With increasing working years, the binaural hearing loss of crushing workers became serious. Serious occupational noise hazards existed in most jobs in open quarries, with crushing workers, mechanists, drilling workers, and blasting workers most seriously jeopardized. Among crushing workers, those working in the first-line or unprotected second?line positions suffered more than the others. Further measures should be taken by the supervision department and the enterprises to control the noise hazards in open quarries.