Exploring the relationship between ambient air pollution and adolescents in South Africa

Abstract

Air pollution is a significant health concern in South Africa, with a growing population contributing to the sustained industrial activities, vehicle emissions, and residential energy use. Outdoor air pollution remains high from industrial processes, mining, and historical urban planning. Despite the implementation of National Ambient Air Quality Standards (NAAQS), many regions in South Africa frequently experience exceedances of these standards. Short- and long-term exposure to air pollution presents an increased risk in developing adverse health effects in adults and children. Adolescence is a period of rapid physical, emotional, and social growth and change. Adolescents are a vulnerable and under-research sub-population group. Research is limited in considering the health effects of air pollution exposure on adolescent health, particularly in low- and middle-income countries (LMICs).

This study aimed to explore the relationship between ambient air pollution and adolescent health and wellbeing in areas where air pollution is a public health concern, and, drawing together this information, provide meaningful insight and recommendations for policy. These aims were addressed by 1) examining the existing literature and research outcomes on adolescent health and wellbeing in LMICs, 2) conducting a health risk assessment on an air pollution hotspot in the Highveld Priority Area (HPA) in South Africa, establishing the risk of developing adverse health outcomes by continued exposure to poor air quality, and 3) quantify the self-reported effects of air pollution exposure on adolescents living in two adjacent towns in the HPA.

A comprehensive literature review was conducted and explored the effects of exposure to criteria air pollutants on adolescent health and wellbeing in LMICs. After screening, sixty articles were included in the review. Multiple adverse health outcomes were described in the literature, and these were grouped into five main categories: pulmonary and respiratory effects; cardiovascular, cardiopulmonary, and haematology effects; metabolic effects; inflammation and cytogenotoxic effects; and miscellaneous health effects. The results of these studies showed that exposure to air pollution – particularly particulate matter (PM) – results in the onset of adverse health conditions, typically in a dose-responsive manner. Adverse health effects included decreased pulmonary function, increased blood pressure, increased prevalence of obesity, and increased risk in developing neurodegenerative conditions. These results highlight the increased susceptibility and vulnerability of adolescents to the development of adverse health outcomes in relation to air pollution exposure.

To address the second objective of this study, using the United States Environmental Protection Agency framework considering hazard identification, exposure assessment, concentration-response analysis, and risk characterization, a comprehensive health risk assessment (HRA) was carried out PM2.5, SO2, and NO2 in the Mpumalanga HPA. Ambient air quality data were obtained for six air quality monitoring sites, from 2009 to 2020. The region is plagued by poor ambient air quality due to intensive mining, industrial, and agricultural activities. It is also an area that experiences a dry and dusty winter climate. Results from the study showed that PM2.5 concentrations frequently exceed the SA NAAQS across all six sites considered, indicating increased risk of respiratory and cardiovascular diseases. A hazard quotient (HQ) is calculated by dividing the measured ambient air quality concentrations for specific averaging periods by existing NAAQS or World Health Organization (WHO) Air Quality Guidelines (AQG) for the same averaging period. HQs > 1 indicate an increased risk in developing non-cancerous health effects. The HQs measured for PM2.5 for the time period considered frequently exceeded one. By contrast, SO2 and NO2 HQs were less than one for the period studied. While this information is invaluable, there were large gaps in the data due to data unavailability over the time period considered. Irrespective of the gaps, the data depicted an alarmingly poor state of air quality in the HPA which deserves immediate attention.

Lastly, the self-reported health effects of adolescents living in a town and adjacent community in the HPA were observed. The town of Secunda and the adjacent community of eMbalenhle were historically established to serve an area of intense mining, coal-burning power plants, and a coal liquefaction plant. Historical (2009 – 2019) ambient air quality data were obtained from proximal air quality monitoring stations. Four local high schools were approached by the researchers for willing participants (233 participants, aged 13 – 17 years old). Once assent and consent were obtained, a socio-economic-demographic questionnaire was filled in by each participant including questions pertaining to other health risk factors such as indoor air pollution (use of biomass as a cooking and heating fuel source in the household), environmental tobacco smoke exposure, pets, and nutritional status. Anthropometric measurements were taken by field assistants. Results from the study showed that, in keeping with the results from the HRA, the ambient air quality in the area frequently exceeded the NAAQS. Adverse respiratory outcomes were reported by adolescents, and this relationship was statistically positively associated with increased number of years living in the area. These results indicate that prolonged exposure to poor ambient air quality is associated with adverse health outcomes in adolescents living in an air pollution hotspot in South Africa, and highlights the need for intervention from policymakers to protect communities from air pollution.

This thesis offers important insights for policymakers and researchers, highlighting the importance of focusing research and preventative efforts on air pollution and health, particularly in the under-researched sub-population of adolescents. By increasing the focus on adolescents and addressing health concerns timeously, the knock-on effect will result in a healthy workforce and healthier population in coming years. The research presented in this thesis is in keeping with the United Nations’ Sustainable Development Goals (SDG), specifically SDG 3 (Good Health and Well-being) and SDG 7 (Affordable and Clean Energy).