Indoor Particulate Matter Pollution on Oxidative Stress Pathways: Role of Chemical and Biological Constituents

The present study aimed to evaluate the relationship between physicochemical characteristics and toxicological assessment of indoor PM bound chemical and biological constituents. The average concentration of both indoor PM10 and PM2.5 exceeded the NAAQS standards of India. Metals of geogenic origin (Fe and Mn) are predominant in PM10 samples, while the metals of anthropogenic origin (Ni, Co, Cd, Pb, Cu, Cr, and Zn) were dominant in PM2.5. Among all analyszd metals, Fe exhibited the maximum concentrations in both sized PM followed by Mn, pb, Cr, Cu and Ni suggesting considerable health risk to the exposed inhabitants due to their ability to generate reactive oxygen species through Fenton’s reaction, mainly responsible for causing PM toxicity. Commonly isolated bacteria and fungi identified in the indoor environment were Bacillus sp., Staphylococcus aureus, Pseudomonas aeruginosa, Aspergillus sp. and Penicillium sp., respectively. Amongst them, Pseudomonas aeruginosa and Aspergillus sp. were found to be predominant in both sized PM revealing a significant health risk due to their association with various respiratory tract infections. The cytotoxic profile of indoor PM and their constituents determined by MTT assay on A549 cells exhibited a significant decrease in cell viability indicating the cytotoxic behavior of particles. Oxidative reactivity of indoor PM in terms of DTT assay showed considerable DTT depletion suggesting the oxidative nature of PM. Results of the present study will be effectual to raise awareness and address the better indoor air quality for the residents.