Chemical composition, mutagenicity, and cytotoxicity of urban submicron particulate matter (PM₁) in Agra, India

This study, conducted in Agra, India, examined the mass concentrations, chemical compositions, and seasonal variations of submicron particles (PM₁). The concentrations of metals, water-soluble inorganic ions (WSIs) including anions (F^-, Cl^-, NO₃^-, SO₄^2-) and cations (Ca²⁺, K⁺, Mg²⁺, NH₄⁺, Na⁺), organic carbon (OC) and elemental carbon (EC) and polycyclic aromatic hydrocarbons (PAHs) in PM₁ extract were determined using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), Ion Chromatography, Thermogravimetric Analysis and Gas Chromatography-Mass Spectrometry (GC-MS) respectively. For morphological observation of PM₁ particles, Field Emission Scanning Electron Microscopy-Energy Dispersive X-ray spectrometry (FESEM-EDS) was used. The annual average concentration of PM₁ was 82.9 ± 33.4 μg/m³, which exceeds the World Health Organisation's (WHO) safe limit for PM_2.5 of 5 μg/m³ by a factor of 17. The PM₁ mass composition included metals (31 %), WSIs (28 %), OC and EC (9.8 %), and PAHs (0.4 %). Winter recorded the highest PM₁ concentration (96.1 ± 25.8 μg/m³), followed by post-monsoon, summer, and monsoon seasons. The average concentration of PAHs was 364.6 ± 226.6 ng/m³. Positive Matrix Factorization (PMF) identified traffic, emissions from biomass/coal and wood combustion, industrial/stationary sources, and secondary aerosols as potential contributors. The Ames test revealed the presence of frameshift mutations and base pair substitutions, especially in winter and post-monsoon. Additionally, PM₁ exhibited cytotoxic effects on V-79 cells, with heightened toxicity during winter and prolonged exposure in other seasons. This study underscores the urgent need to address local emission sources and establish regulatory standards for PM₁ in urban areas.