Assessment of oxidative potential and chemical characterization of total suspended particulate matter (TSPM) in ambient and indoor air pollutants

Airborne particulate matter (PM) from both indoor and ambient sources is a major contributor to air pollution and poses serious health risks. Traditional PM mass concentration measurements fail to understand the toxicological relevance or chemical composition of respective PM, making it difficult to assess their actual health impacts. A major struggle lies in identifying the sources and understanding the oxidative stress mechanism triggered by the exposure of PM. In this study, we address the gap by evaluating the oxidative potential and chemical composition of total suspended particulate matter (TSPM) emitted from various indoor sources, including incense sticks, mosquito coils, cow dung cakes, charcoal, and ambient air. TSPM samples from indoor sources were collected using a high-volume air sampler (Envirotech APM 460) in a controlled experimental chamber, while the TSPM of ambient air was collected from a high-traffic area (Irwin Road, Mysuru) to represent typical urban outdoor air. All samples were analyzed for mass concentration and subjected to chemical characterization. The oxidative potential of TSPM was assessed using dithiothreitol (DTT) and ascorbic acid (AA), whereas the immunoassay has been used to measure the level of phosphocholine (Ox-PCs), a biomarker of oxidative damage. Statistical analysis was performed using IBM SPSS (Version 29.0), while GraphPad Prism (Version 8.0) was used for data visualization and figure representation. Our results reveal that cow dung cakes and mosquito coil emissions significantly elevate the reactive oxygen species (ROS) and Ox-PCs, suggesting a heightened risk of oxidative stress. These findings underscore the critical need for targeted mitigation strategies and firmer indoor air quality regulations, particularly focusing on biomass air pollution to reduce the public health risks.