Figure 3. PM 2.5 induces apoptosis of keratinocytes. (a) Cell viability of HaCaT cells treated with 0-400 μg/ml of PM2.5 for 24 h. (b) Apoptotic/necrotic cells were determined using Hoechst 33342 and Propidium iodide staining. All plots show the mean±SD (n=3). *p<0.05 vs. untreated cells.