Fig. 1

PM at a low concentration does not decrease cell viability. The cell viability of BEAS-2B cells after urban particulate matter (PM) exposure was assayed using a CCK-8 assay according to the manufacturer’s instructions. The cells were incubated for 24 h with various concentrations of PM as follows: 10, 50, 100, 200 and 400 μg/ml. The data are expressed as the mean ± SD of three independent experiments. ^*P < 0.05 and ^**P < 0.01 versus P0 (0 μg/ml)