个体防护下噪声作业人群3年高频听阈动态观察
Three Years' Dynamic Observation of High Frequency Hearing Threshold in Noise Exposure Workers with Individual Hearing Protection
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摘要:
目的 研究采用个体听力防护措施的噪声作业人群的高频听阈动态变化,探讨其相关规律,为临床实践和相关标准的制定提供职业流行病学依据。 方法 选择上海地区5家噪声超标≥85 dB(A)并执行听力保护计划的企业,收集其中355人、698耳的连续3年4次纯音听力测试结果进行统计分析。 结果 全体研究对象3年4次语频听阈值均≤25 dB(HL),未见明显变化,高频听阈值随着工作时间的增加而增高,不同工龄组3年间高频平均听阈值亦呈逐年上升趋势。根据初次纯音听阈测试结果,高频听力正常、轻度高频受损和观察对象的高频听阈平均值均逐年上升,其中听力正常者高频听阈值的增高最为显著, 3年后的测试值与初次测试值的差异为(4.14& #177;3.98)dB(HL)。 结论 全体研究对象3年4次高频听阈值每年增高<2 dB(HL),在噪声作业环境中采用的个体听力防护措施,可使作业人员的听力变化控制在较小范围内;提示噪声作业在岗期间的健康监护周期可延长至2年或2年以上。 Abstract:Objective To study the tendency of high frequency hearing threshold in noise exposure workers under in dividual hearing protection and discuss relevant regulations in order to provide epidemiological evidence for occupational noise protection practice and making relative criteria. Methods A total of 698 ears of 355 workers received 4 times of pure tone audiometer tests during the period of 3 years in 5 enterprises in Shanghai, where occupational noise levels were over the national limitation≥ 85dB(A) and hearing conservation programs were carried out. The test results were analyzed statistically. Results The average of low-frequency hearing threshold in all selected workers was below 25dB(HL) over the 4 tests, and no significant change was observed. The average of high-frequency hearing threshold increased with the length of service, and the yearly average of high frequency hearing threshold increased within the groups with different length of service over the 3 years' observation. Comparing with the first hearing test result, the averages of high frequency hearing threshold of the subjects with normal high frequency hearing, mild high frequency hearing impairment, or subjects under surveillance were increased by year and that of the normal group increased (4.14& #177;3.98) dB(HL) in 3 years. Conclusion The yearly variation of average high frequency hearing threshold among all subjects was less than 2 dB(HL), which indicated that individual hearing protection device assisted noise exposure workers' hearing loss more controllable. So the period of health surveillance for noise exposure workers in service may extend to 2 years or longer.
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