Characteristics and sources of water-soluble ionic associated with PM2.5 particles and cytotoxicity effects using MTT assay in Tehran, Iran

Air pollution with its harmful effects has become the most important environmental problem in Tehran city, Iran. The main aim of the present study was to investigate the physical and chemical characteristics of particulate matters (PM) such as scanning electron microscopy (SEM), coupled with energy dispersive X-ray analysis (SEM-EDX), dynamic light scattering measurement (DLS), and Thermal gravimetric analyses (TGA) analysis and determine the ionic composition of cations (Na+, K+, Mg2+, and Ca2+) and anions (Cl−, SO42−, NO3−, and F−), and principal component analysis (PCA) analysis in different stations, during four types of seasons in 2016. The cell viability of human A549 cells of water-soluble and organic extract from PM2.5 particles was tested using the MTT assay. The results showed that the SEM image of PM2.5 particles was a size range of 1.44–2.03 μm and EDX analysis shows that the presence of Si, Ca, Na, and Mg with a higher amount in the structure of PM2.5 particles. The total concentration of ions in PM2.5 for urban stations during spring, summer, autumn, and winter was 7.01 ± 3.2 μg/m3, 6.86 ± 2.85 μg/m3, 7.46 ± 4.85 μg/m3, 8.49 ± 4.1 μg/m3, respectively. The seasonal concentrations of ionic compounds for urban and traffic stations were higher in winter and autumn than in spring and summer. The highest positive correlation for PM2.5 was identified between ionic species in the traffic station, NO3-SO4 (R = 0.93), Cl-SO4 (R = 0.61), Cl-NO3 (R = 0.67), Mg Ca (R = 0.67), Na Mg (R = 0.68), and K Mg (R = 0.57). Toxicity studies showed that a wide range of cytotoxicity values were obtained for organic and water-soluble extractable PM2.5, from 45 to 91% in summer and 36 to 70% in winter, for the three stations.