Worker’s knowledge and perception on occupational exposure related to emissions at wastewater treatment plants, in the City of Tshwane, South Africa

Abstract

Background Workers at WWTPs are responsible for ensuring there is daily operations and maintenance. Workers are exposed to a variety of biological, chemical and physical hazards that emanate from wastewater and treatment activities. Aim The study aimed at evaluating the knowledge and perception of WWTP workers occupational exposure to bioaerosols, volatile organic compounds (VOCs) and odours, including their self-reported health symptoms associated with these emissions, from three WWTPs in the City of Tshwane, Gauteng. Methods A cross-sectional quantitative study design was conducted among workers at three wastewater treatment plants (WWTPs), in the city of Tshwane. A total of 32 participants were recruited via convenience sampling: 12 from WWTP A, 10 from WWTP B and 10 from WWTP. All the eligible workers at each study site were invited to participate in the study. Participation was voluntary, and written informed consent was obtained prior to data collection. Data was collected using a self-administered questionnaire (n=32), which assessed knowledge, perception, and self-reported symptoms related to exposure to bioaerosols, VOCs, and odours (BVOs). Descriptive statistical analysis and correlation analysis were used to explore associations between demographic variables and both knowledge and perception. Self-reported symptoms were recorded for all participants. Data analysis was performed using SPSS software (version 29.0.0). Ethics clearance was obtained from the University of the Witwatersrand Human Research Ethics committee (Medical): Certificate No. M240107 M240517-B-0001. Results The findings indicated that workers demonstrated limited knowledge regarding bioaerosols, VOCs, and combined BVO emissions, including their associated health effects. Fewer than vi 63% of responses were accurately identified the sources of BVOs and associated health outcomes. Despite this knowledge gap, workers showed strong awareness of key safety practices: 97% recognized the importance of showering and changing clothes after a shift, and 84% correctly identifying the aeration process as the highest-risk activity for exposure to airborne droplets. Over 44% of the participants reported experiencing flu-like, respiratory, irritant-related, or gastrointestinal symptoms, one to three times within the past six months. Correlation analyses showed generally weak or no associations, between demographic variables and workers’ knowledge or perception of BVO occupational exposure. However, a statistically significant negative correlation was observed between education level and knowledge of WWTP emissions (r = −0.037, p = 0.038), indicating that higher education was modestly associated with lower knowledge scores possibly reflecting overconfidence or information gaps. Additionally, a significant correlation analysis found between educational level and the perception that eating anywhere in the plant is acceptable (r=−0.410, p=0.020), suggesting greater adherence to safety protocols among more educated workers. A moderate positive correlation was also found between the type of employment and the perception that air quality affects health (r = 0.365, p = 0.040), suggesting that certain job tasks may be linked to increased awareness of air-related health risks. Conclusion The findings highlight the need for comprehensive occupational health strategies and programs within wastewater treatment facilities, particularly those that bridge the gap between knowledge and practical risk perception related to bioaerosols, VOCs, and odours (BVOs). There is limited understanding of BVO-related health risks among workers, despite high compliance with certain safety practices, this suggest that current training programs may be insufficient in addressing invisible or long-term chemical and biological hazards. Tailored educational interventions that incorporate both biological and chemical exposure risks are essential to enhance hazard recognition and promote preventative behaviours across all employment levels. Future research should focus on longitudinal studies to evaluate the long-term health effects of chronic BVO exposure among WWTP workers, particularly using objective clinical or biomonitoring data alongside self-reported symptoms. Additionally, there is a need to explore organizational and psychosocial factors such as management practices, safety vii culture, and risk communication efficacy that may influence workers' engagement with occupational health protocols. Investigating the effectiveness of targeted training modules and behavioural interventions could provide actionable insights for policy development and risk mitigation in similar high-exposure occupational settings.