Health Risk Assessment of Sulphur Dioxide Emissions in Mangaung, Bloemfontein, South Africa (2023)

Abstract

Introduction: Air pollution poses serious environmental and public health challenges in many South African cities. In Mangaung, sulphur dioxide (SO₂) is one of the major pollutants linked to domestic fuel burning, traffic emissions, and meteorological conditions, especially during winter. Vulnerable groups such as children and the elderly are particularly at risk of adverse health outcomes from prolonged or high-level exposure. Aim: The study aimed to assess the health risks associated with ambient SO₂ emissions in Mangaung, based on 2023 data from the Pelonomi air quality monitoring station. Methods: A descriptive and quantitative approach was used, relying on secondary SO₂ concentration data obtained from the South African Air Quality Information System (SAAQIS). The data were analysed to determine hourly, daily, monthly, and seasonal trends. One-way ANOVA and Bonferroni post-hoc tests were applied to identify statistically significant seasonal SO2 differences. A scenario-based health risk assessment was conducted for toddlers and elderly populations using the USEPA’s noncarcinogenic risk model. Findings: The results showed significant seasonal variation, with SO₂ concentrations peaking in winter and remaining lowest in summer. While all values were below the South African National Ambient Air Quality Standards (NAAQS), many exceeded the World Health Organization’s 24-hour guideline of 20 μg/m³. The calculated hazard quotient (HQ) values for both toddlers (0.0674) and the elderly (0.0824) were below 1, indicating low long-term health risk. However, repeated short-term peaks observed in the hourly and daily averages suggest potential health concerns for sensitive groups during colder months. Conclusion: Although long-term exposure to SO₂ in Mangaung does not currently pose a significant health risk, short- term exposure spikes—particularly during winter—may still lead to respiratory issues among vulnerable populations. The use of national standards alone may underestimate these risks. Recommendations: The study recommends aligning national air quality standards with WHO guidelines, expanding monitoring networks in high-risk areas, promoting clean energy alternatives for households, and improving public awareness of the health impacts of SO₂ pollution. These actions are necessary to safeguard public health and support sustainable urban air quality management in Mangaung.