Fig. 3

Relative cell viability (metabolic activity) measured by Alamar Blue assay in human lung epithelial A549 cells exposed to NMs for 3 (A, C, E) and 24 (B, D, F) hours. Data are presented as mean values from at least 3 independent experiments (with two technical replicates in each independent experiment) + / − SD, relative to negative control (NC). Statistically significant difference respect to NC according to one-way ANOVA with Dunnett’s post-hoc test, *p < 0.05, **p < 0.01, ***p < 0.001