THE EFFECT OF EXCESSIVE OF NOISE EXPOSURE ON HEARING IMPAIRMENT AMONG CRUSHING STONE WORKERS

摘要

The purposes of this study were to evaluate noise exposure and its effect on hearing ability of the exposed workers. Noise exposure among stone crushing workers was measured by using sound level meter at the workplace areas. The hearing impairment of workers was evaluated by audiometer. There were thirteen sampling points at the crushed stone operations for monitoring noise using a sound level meter. The result revealed that there were 9 sampling points that the noise level was exceeded the Thailand occupational health safety and environment standards at 90 dB (A) for eight working hours. They were 96.3 dB (A) Leq at stone delivery truck parking area (near stone feeding area) 4, 105.7 dB(A) Leq at stone feeding area 4, 101.4 dB(A) Leq at stone feeding area 5, 102.9 dB(A) Leq at vibrating screen 4, 109.1 dB(A) Leq at vibrating screen, 99.1 dB(A) Leq at rest area near stone feeding area 7, 100.5 dB(A) Leq at stone feeding area 7, 99.8 dB(A) Leq at vibrating screen 7 and 95.0 dB(A) Leq at hopper 7. The audiometric data revealed that there were 34 workers suffered from hearing loss and 51 workers showed normal hearing ability. In the hearing impairment group, there were hearing loss in slight level (n=12), moderate level (n=10) and severe level (n=5). This industry already has selection and use of hearing protection devices and periodic audiometric evaluation for the workers. Therefore, the hearing conservation program including engineering and administrative controls such as using sound absorption materials, modifying work rotation system should be conducted in the stone feeder, jaw crusher area and vibrating screen.