Number of neutrophils and macrophages in BALF of mice at 4 h and 24 h post-exposure to ENCF-1 and ENCF-4 PM (100 μg) by oropharyngeal aspiration. (A) neutrophils and (B) macrophages. Data are means ± SEM (n = 5–6 in each group). *p < 0.05 compared with the saline-exposed negative control group from the same time point. #p < 0.05 compared with the ENCF-4 PM exposed group from the same time point. Mice exposed to 2 μg of LPS served as a positive control.