不同允许暴露极限对超过25分贝声级的听力阈值水平的影响。

The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA.

作者信息

Sayapathi Balachandar S, Su Anselm Ting, Koh David

机构信息

Centre for Occupational and Environmental Health, University of Malaya, Kuala Lumpur, Malaysia ; Department of Ministry of Health, Kuala Lumpur, Malaysia.

Department of Community Medicine and Public Health, Faculty of Medicine and Health Sciences, University Malaysia Sarawak, Sarawak, Malaysia ; Department of Hygiene, School of Medicine, Wakayama Medical University, Wakayama, Japan.

出版信息

Iran Red Crescent Med J. 2014 Oct 5;16(10):e15520. doi: 10.5812/ircmj.15520. eCollection 2014 Oct.

DOI:10.5812/ircmj.15520

PMID:25763196

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC4329756/

Abstract

BACKGROUND

Development of noise-induced hearing loss is reliant on a few factors such as frequency, intensity, and duration of noise exposure. The occurrence of this occupational malady has doubled from 120 million to 250 million in a decade. Countries such as Malaysia, India, and the US have adopted 90 dBA as the permissible exposure limit. According to the US Occupational Safety and Health Administration (OSHA), the exposure limit for noise is 90 dBA, while that of the US National Institute of Occupational Safety and Health (NIOSH) is 85 dBA for 8 hours of noise exposure.

OBJECTIVES

This study aimed to assess the development of hearing threshold levels beyond 25 dBA on adoption of 85 dBA as the permissible exposure limit compared to 90 dBA.

PATIENTS AND METHODS

This is an intervention study done on two automobile factories. There were 203 employees exposed to noise levels beyond the action level. Hearing protection devices were distributed to reduce noise levels to a level between the permissible exposure limit and action level. The permissible exposure limits were 90 and 85 dBA in factories 1 and 2, respectively, while the action levels were 85 and 80 dBA, respectively. The hearing threshold levels of participants were measured at baseline and at first month of postshift exposure of noise. The outcome was measured by a manual audiometer. McNemar and chi-square tests were used in the statistical analysis.

RESULTS

We found that hearing threshold levels of more than 25 dBA has changed significantly from pre-intervention to post-intervention among participants from both factories (3000 Hz for the right ear and 2000 Hz for the left ear). There was a statistically significant association between participants at 3000 Hz on the right ear at 'deteriorated' level ( χ² (1) = 4.08, φ = - 0.142, P = 0.043), whereas there was worsening of hearing threshold beyond 25 dBA among those embraced 90 dBA.

CONCLUSIONS

The adoption of 85 dBA as the permissible exposure limit has preserved hearing threshold level among participants at 3000 Hz compared to those who embraced 90 dBA.

摘要

背景

噪声性听力损失的发展取决于几个因素，如噪声暴露的频率、强度和持续时间。在十年间，这种职业病的发病率从1.2亿增加了一倍，达到2.5亿。马来西亚、印度和美国等国家已采用90分贝作为允许暴露限值。根据美国职业安全与健康管理局（OSHA）的规定，噪声的暴露限值为90分贝，而美国国家职业安全与健康研究所（NIOSH）规定，8小时噪声暴露的限值为85分贝。

目的

本研究旨在评估采用85分贝作为允许暴露限值与90分贝相比，听力阈值水平超过25分贝的发展情况。

患者与方法

这是一项在两家汽车工厂进行的干预研究。有203名员工暴露于超过行动水平的噪声中。发放听力保护装置以将噪声水平降低到允许暴露限值和行动水平之间。工厂1和工厂2的允许暴露限值分别为90分贝和85分贝，而行动水平分别为85分贝和80分贝。在基线时以及噪声暴露后第一个月测量参与者的听力阈值水平。结果通过手动听力计测量。在统计分析中使用了麦克尼马尔检验和卡方检验。

结果

我们发现，两家工厂的参与者从干预前到干预后，超过25分贝的听力阈值水平有显著变化（右耳为3000赫兹，左耳为2000赫兹）。在“恶化”水平下，右耳3000赫兹的参与者之间存在统计学上的显著关联（χ²(1)=4.08，φ=-0.142，P=0.043），而接受90分贝的参与者中，听力阈值超过25分贝的情况有所恶化。