Occupational Noise Exposure and its effects on hearing among Hospital Support Workers at Jigme Dorji Wangchuck National Referral Hospital, Thimphu, Bhutan: A Cross-Sectional Study

Abstract

Background: Occupational noise-induced hearing loss (NIHL) is documented in mining and manufacturing but remains understudied in hospital settings. Support workers in laundry units, oxygen plants, and Central Sterile Supply Departments (CSSDs) face hazardous noise exposure but remain underrepresented in hearing conservation research. Objective: To assess occupational noise exposure and its impact among support workers in high-noise departments at Jigme Dorji Wangchuck National Referral Hospital (JDWNRH), Bhutan. Methods: The cross-sectional study included 49 support workers from the oxygen plant, laundry unit, and CSSD. Data were collected through structured questionnaires, noise dosimetry, and pure-tone audiometry by an audiologist. Air and bone conduction thresholds were measured at 250, 500, 1000, 2000, 4000, and 8000 Hz. Occupational NIHL (ONIHL) was defined by a sensorineural notch at 4 kHz with recovery at 8 kHz. Statistical analysis used chi-squared tests, with significance set at p < 0.05. Results: ONIHL prevalence was in the oxygen plant (85.7%), laundry unit (85.0%), and CSSD (73.3%). Severity increased with longer exposure duration, although audiometric changes were observed among younger and less-tenured workers. Hearing protection use was low, in CSSD (6.6%) and the oxygen plant (7.1%). Men had higher rates of mild-to-moderate hearing loss, while workers aged 40–49 years showed the highest prevalence of moderate-to-severe impairment. Conclusion: The findings highlight an occupational hearing health gap at JDWNRH. The high prevalence of ONIHL and low use of hearing protection underscore the need for engineering controls, administrative safeguards, mandatory audiometric surveillance, hearing protection, and effective occupational noise safety measures.