Evaluating the Effectiveness of Earplugs in Preventing Noise-Induced Hearing Loss in an Auto Parts Factory in China.

Wei Gong,Thais C Morata,Huiling Amy Feng,Liangliang Zhao,Wei Qiu,Wei Qiu,Baoli Zhu,Ling Li

doi:10.3390/ijerph18137190

Abstract

A survey was administered to 385 noise-exposed workers from an auto parts factory and 1268 non-noise-exposed health department employees in China. Individual 8 h A-weighted equivalent sound levels (LAeq,8h), earplug personal attenuation ratings (PARs), and pure-tone audiometric tests were performed. The average LAeq,8h of noise-exposed workers was 87 dB (A) with a mean PAR of 7 dB. The prevalence of high-frequency hearing loss was 65% for noise-exposed workers and 33% for the non-noise-exposed employees. The use of earplugs had no observable effect on the prevalence of high-frequency hearing loss of the study participants (OR 0.964, 95% CI 0.925–1.005, p = 0.085). No significant relationship between the effectiveness offered by earplug use and high-frequency hearing thresholds at 3, 4, and 6 kHz was found (t = −1.54, p = 0.125). The mandatory requirement of earplug use without individualized training on how to wear HPDs correctly had no detectable effect on the prevention of hearing loss at the auto parts factory. The hearing conservation program at the surveyed factory was not effective. Periodic hearing tests, earplug fit testing, expanding the offer of different types of hearing protection, and employee education about the importance of protecting their hearing were recommended to the occupational health and safety program.

Highlights

Noise-induced hearing loss (NIHL) is the third most prevalent chronic physical condition among adults in the United States [1]
A total of 385 noise-exposed workers and 1268 non-noise-exposed employees participated in this study
The mean personal attenuation ratings (PARs) offered by the earplugs was 7 dB, which could theoretically protect 53.7% of the 315 noise-exposed workers by reducing in-the-ear noise exposure to less than 85 dB (A)

Summary

Introduction

Noise-induced hearing loss (NIHL) is the third most prevalent chronic physical condition among adults in the United States [1]. In the field of occupational health, a hierarchy of controls that prioritizes controlling the source of exposure is recommended for being more effective, while less burdensome to workers and less dependent on behavior than those involving personal protective equipment. A large epidemiologic evaluation, which examined the association between self-reported hearing protection use at work and hearing thresholds of. 19,911 noise-exposed U.S workers, observed that hearing threshold differences of workers who reported “never” versus “always” wearing hearing protection was marginally significant. A significant linear trend towards increased risk of high-frequency threshold shift with decreased use of hearing protection was observed [5]. The evidence of the effectiveness of HPDs seems dependent on several factors such as inconsistencies in earplug use, lack of HPD alternatives, the skill of the worker to fit a device, and the instructions for insertion [4]

Methods

Results

Discussion

Conclusion