Human Health Risk Assessment of PM2.5, NO2, and SO2 and its Impact on Mortality in Nkangala and Gert Sibande, South Africa

Introduction: Located in Mpumalanga’s Highveld Priority Area (HPA), Nkangala and Gert Sibande are well‑known for sustained exposure to high levels of air pollution, which is linked to adverse health effects. We aimed to carry out a comprehensive health risk assessment to determine to what extent air pollution impacts mortality rates in Nkangala and Gert Sibande. Methods: A standardized US EPA health risk assessment (HRA) protocol was used to calculate hazard quotients (HQs), using pollutant concentration, average body mass and inhalation rates, and pollutant concentrations (2009–2018) for PM2.5, SO2, and NO2 from three air quality monitoring stations in Nkangala and three in Gert Sibande. Cause‑specific mortality rates were compared with the HQs. Results: The study findings revealed frequent exceedances of WHO air quality guidelines for PM2.5, NO2, and SO2 in Nkangala and Gert Sibande, despite compliance with less stringent South African NAAQS reference standards. Gert Sibande consistently had higher pollutant levels and associated hazard quotients (HQs) and greater attributable mortality, particularly for lower respiratory infections (LRIs), stroke, and chronic obstructive pulmonary disease (COPD). Secunda, in Gert Sibande, showed especially high short‑term PM2.5 exposure risks. Discussion: Continued exposure to air pollution has been associated with the development of multiple health concerns, as well as increased mortality. This study suggests that SO2 and NO2 exposure is not as great a concern for populations living in the HPA. However, continuous monitoring is needed to ensure these pollutants’ concentrations do not increase in the future. Conclusions: These findings highlight the history of inadequate South African national reference standards in protecting public health and the need for stricter air quality regulations that align with international standards. PM2.5 is a major health concern for people living in the HPA, South Africa. Air quality management should be bolstered to decrease the amount of PM2.5 in the area.