Impaired pulmonary function as determined by Snapshot and Quick-prime 3 perturbation after MWCNT instillation. The Snapshot and Quick-prime3 perturbations were performed in tracheotomized C57BL/6 mice instilled with increasing doses of MWCNTs. Since Snapshot perturbation measures the lung as a single compartment, the parameters, R (A), E (B), and C (C), are indicative of the whole respiratory system including lung and chest wall. On the other hand, Quick-prime 3 perturbation measures the lung as multiple compartments. The parameters can differentiate between central airway (Rn (D)) and peripheral lung tissue (G (E) and eta (F)). The mean ± SEM of six mice per group are shown, *p < 0.05 and ** p < 0.01 compared with the naïve mice, # p < 0.05 and ## p < 0.01 compared with the vehicle control (10% surfactant in saline) mice; + p < 0.05, ++ p < 0.01, and +++ p < 0.001 compared between two groups. No statistically significant differences were found between naïve and vehicle treated mice.