ABSTRACT:
Socioeconomic conditions in low-income settlements of the Western Cape have potential implications for indoor air quality. As part of a broader project ‘Building Healthier Communities’ that aims to evaluate living conditions in low-income households with children under five years old, this study determined the geochemical composition, Hazard Indices, and sources of fine particulate matter (PM2.5) collected between November 2022 and March 2024. Indoor PM2.5 samples were collected across 13 low-income settlements using Ultrasonic Personal Air Sampler (UPAS) equipped with PTFE filters and analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Scanning Electron Microscopy (SEM). Most abundant elements included Al, Fe, Zn, Ba, Mn, As, Sr, Cd, and Pb, with Fe concentrations reaching peak concentrations of 54.5 µg/m³. Potentially toxic elements Pb, As, Se, Cd, Cr, Cu and V were also detected in these indoor samples. Enrichment Factors (EF) indicated a crustal origin (EF < 10) for Mn and Fe in PM2.5, while Zn, Pb, As, Cd, Cu, Ba, Cr, and Ni (EF > 10) appear to receive an anthropogenic addition. Calculated metal content-based Hazard Indices point to the occurrence of health threats, particularly for children. Positive Matrix Factorization identified three pollution sources for the particles that are partially unexpected for indoor samples: (i) manufacturing and steel industries, which accounted for 18% of the total analysed particles; (ii) solid waste burning (58%); and (iii) traffic-related emissions and oil combustion (24%). Implementing stricter regulations on local combustion sources, establishing metal-specific emission guidelines at a Southern African scale, and enhancing public awareness on the health risks of solid waste burning are important strategies to reduce indoor PM2.5 levels in low-income communities of the Western Cape.