Optimizing Worker Safety: Modelling Age, Exposure Duration and Noise Effects on Hearing Threshold in Quarry Workers

Abstract

Quarries play a vital role in the construction industry. However, studies indicate that the age of quarry workers and their years of exposure to quarry activities contribute to hearing issues. Data on the effects of noise and related factors on hearing damage among Nigerian quarry workers are limited. This study aimed to investigate the effect of age, exposure duration, and noise levels in quarries on workers' hearing thresholds. In 2022, 204 quarry workers aged 18 to 65 were randomly selected from four quarries in the southwestern Nigeria. A follow-up study in 2023 included 185 workers. Questionnaires captured their age and exposure years, while digital sound level meter was used to measure noise levels. Hearing thresholds were tested at eight frequencies (250 Hz to 8 kHz) using an audiogram. Eight regression models were developed using response surface methodology to predict the effects of age, exposure, and noise on hearing thresholds. Noise levels at the quarries ranged from 87.3 to 116.98 dB(A), exceeding the permissible 85 dB(A) limit. The models predicted R² values between 0.71 and 0.82. Safe hearing thresholds were predicted for the workers aged ≤52 years and with ≤32 years of exposure. The models showed strong predictability, making them useful for planning recruitment and operational policies in the quarry industry. It was concluded that age, exposure duration, and noise levels significantly affect quarry workers' hearing thresholds.