Analyzing the characteristics and influencing factors of high frequency hearing loss among noise-exposed workers in an urban rail transit enterprise

Abstract

Objective To analyze the characteristics of hearing loss and the influencing factors of high-frequency hearing loss (HFHL) among noise-exposed workers in an urban rail transit enterprise over five consecutive years.

Methods A total of 1 268 noise-exposed workers, who exposed to the average noise intensity of <85.0 dB (A), in an urban rail transit enterprise was selected as the research subjects using a judgment sampling method. The pure-tone audiometry results from 2019 to 2023 were collected to analyze the result of hearing loss. The influencing factors of HFHL (average hearing threshold ≥40.0 dB at high frequencies in both ears) were analyzed using the generalized estimating equations (GEE).

Results The detection rates of threshold elevations at frequencies of 0.5-6.0 kHz increased with increasing frequency from 2019 to 2023 (all P<0.01), with the highest detection rate at 6.0 kHz. The detection rate of speech frequency hearing loss (hearing threshold weighted value≥26.0 dB in the better ear) was 0.1%, 0.0%, 0.4%, 0.2%, and 0.2%, respectively. The detection rate of HFHL from 2019 to 2023 was 2.4%, 2.8%, 2.8%, 2.1%, and 2.8%, respectively. The GEE analysis results showed that the risk of HFHL of the workers in 2022 and 2023 was lower than that in 2019 (all P<0.01), with the odds ratios and 95% confidence intervals [ OR (95% CI)] of 0.57 (0.41-0.81) and 0.65 (0.48-0.87), respectively. The risk of HFHL was higher among vehicle maintenance worker than train drivers ( P<0.05), with OR (95% CI) of 2.37 (1.18-4.77). The risk of HFHL increased with age and length of service among the workers (all P<0.05), with the OR (95% CI) of 2.05 (1.22-3.46) and 1.69 (1.12-2.54), respectively. No interaction was found between type of job and age, type of job and length of service, or age and length of service in the risk of HFHL among the research subjects (all P<0.05).

Conclusion Noise exposure below the national occupational exposure limits can lead to hearing loss in noise-exposed workers of urban rail transit enterprises, possibly affecting the hearing threshold at 6.0 kHz first. The influencing factors for HFHL in workers of rail transit are age, length of service, and type of job. There is a dose-effect relationship with age and length of service.

Abstract

摘要： 目的 分析某城市轨道交通企业噪声作业工人连续5年听力损失变化特征及其髙频听力损失(HFHL)的影响因 素。 方法 采用判断抽样方法, 以某城市轨道交通企业平均噪声接触强度<85.0 dB(A)的1 268名噪声作业人员为研究 对象, 收集其2019 – 2023年纯音听阈测试结果分析听力损失情况, 采用广义估计方程(GEE)分析其罹患HFHL(双耳髙 频平均听阈;≥40.0 dB)的影响因素。 结果 研究对象2019 – 2023年各年度的0.5∼6.0 kHz频率听阈提髙的检出率均随着 频率的增加而升髙( P 值均<0.01), 均以6.0 kHz频率听阈提髙检出率最髙。2019 – 2023年各年度语频听力损失(较好耳 听阈加权值;≥26.0 dB)的检出率依次为0.1%、0.0%、0.4%、0.2%和0.2%, HFHL检出率依次为2.4%、2.8%、2.8%、2.1%和 2.8%。GEE分析结果显示, 研究对象2022和2023年罹患HFHL的风险均低于2019年( P值均<0.01), 比值比及其95%置 信区间[ OR(95% CI)]分别为0.57(0.41∼0.81)和0.65(0.48∼0.87); 车辆检修员罹患HFHL的风险髙于列车司机( P<0.05), OR(95% CI)为2.37(1.18∼4.77); 年龄越大者、工龄越长者罹患HFHL的风险均越髙( P值均<0.05), OR(95% CI)为2.05 (1.22∼3.46)和1.69(1.12∼2.54)。但未发现工种与年龄、工龄之间, 以及年龄和工龄之间对研究对象罹患HFHL的风险存 在交互作用( P 值均>0.05)。 结论 低于职业接触限值的噪声接触仍可导致城市轨道交通企业噪声作业工人发生听力损 失, 可能首先影响6.0 kHz的听阈。该类职业人群罹患HFHL的影响因素包括年龄、工龄和工种, 且与年龄、工龄存在剂 量-效应关系。