Chemical Characterization of Trace Elements in PM_2.5 and PM₁₀ and Their Source Apportionment by PMF Modelling with...

This study assessed particulate matter to quantify trace elements, and source apportionment using the positive matrix factorization (PMF) receptor model, enrichment factor (EF), and health risk assessment of toxic trace elements. The mean 24-h gravimetrically measured PM_2.5 and PM₁₀ concentrations were 66.87 µg/m³ and 121.44 µg/m³, respectively, exceeding the standard limits. The 22 trace elements detected by inductively coupled plasma optical emission spectroscopy (ICP-OES) accounted for 1.12% of the total PM, raising health concerns. The percent contribution of sources by the PMF model for PM_2.5 and PM₁₀ is approximately 27% and 40% crustal emissions, 30% and 29% road dust, 18% and 15% secondary aerosols, 13% and 7% vehicular emissions, 6% and 4% industries & mining activities, and 6% and 5% marine sources, respectively. Although crustal emissions and road dust appeared to be significant contributors, as indicated by the combined evaluation of EF and PMF results, these factors were found to be mixtures of resuspended dust and emissions, rather than purely crustal material, due to the strong dominance of fine particles from anthropogenic activities and secondary processes. Further, the observed carcinogenic risk (CR) values were higher for elements Cr < As < Cd < Ni < Pb in PM_2.5 and PM₁₀ for children and adults, respectively, than the USEPA limits of 1 × 10^-6 to 1 × 10^-4. Children were more susceptible to health risks than adults, with higher hazard quotients (HQs) and CR values for PM_2.5, making it more potent than PM₁₀. This study advances current understanding by coupling size-resolved trace element chemistry with receptor-based source apportionment and quantitative health risk assessment for the understudied Aravalli foothill urban environment. This also provides a comprehensive understanding of trace elements contributing to particulate matter and the associated health risks, with crucial insights for air quality management and public health.