Fig. 1

Effect of chebulic acid (CA) and urban particulate matter (UPM; NIST 1648a) on cell viability. Effect of CA on the human pulmonary alveolar epithelial cell (NCI-H441) viability after 24 h (a). Cytotoxicity of UPM (0.1, 1, and 10 μg/mL) on NCI-H441 after 24 h (b). Effect of exposure to UPM (10, 50, and 100 μg/mL) on NCI-H441 for 6 h (c). Data are means ± SD of three experiments with triplicate samples and different letters indicate significant differences at p < 0.05 by Tukey’s multiple comparisons test