Assessment of Occupational Noise Exposure Effects on Cardiovascular Functions of Saw-Mill Workers

Abstract

Aim: We aimed at assessing the effects of occupational noise exposure on cardiovascular functions of saw-mill workers in Nnewi metropolis, Anambra State, Nigeria. Study Design: This is a cross-sectional study comparing saw-mill workers occupationally exposed to intense noise levels with unexposed control. Place and Duration of Study: Department of Human Physiology, Nnamdi Azikiwe University, between February, 2019 and March 2020. Methodology:  Fifty saw-mill workers (26 males, 24 females), of mean age 30.84 ± 6.26 years and 50 controls (18 males, 32 females; mean age, 26.32 ± 6.32 years) participated in the study. The mean ambient noise level for each site was obtained with a sound meter measurement prior to cardiovascular function test for each participant. The noise level, blood pressure (BP) and heart rate (HR) measurements were done for the saw-mill workers when the machines were in operation. Other parameters such as mean arterial pressure (MAP), pulse pressure (PP), rate pressure product (RPP), cardiac output (CO) and oxygen consumption (VO2) were determined using appropriate scientific equations. Results: Saw-mill workers indicated significantly higher (p<0.05) mean systolic BP, diastolic BP, MAP, RPP and PP, but lower (p<0.05) mean CO, and VO2 compared with the control. No significant difference was observed in HR between the two groups. Incidences of both systolic and diastolic hypertension and abnormally high MAP were greater in sawmill workers compared to the control. The risk of systolic hypertension, abnormally high MAP, among sawmill workers was higher compared to the control. Conclusion: Our study revealed that hypertension and other abnormal cardiovascular outcomes were more prevalent in the noise-exposed saw-mill workers compared to unexposed control. These findings may serve to increase workers’ awareness about effects of occupationally noisy environments on their health and suggest the need to reduce workplace noise levels in order to improve their cardiovascular health.