Effect of multi-walled carbon nanotube (MWCNT) inhalation on pulmonary permeability at different time points after exposure. Albumin (mg/dL), an indication of a loss of epithelial barrier integrity, was measured from the first fraction of collected bronchoalveolar lavage fluid. Data are expressed as percent (%) change from respective sham (dashed line – 100%). N.D. – not determined. *p<0.05 vs. respective sham; #p<0.05 vs. other MWCNT depositions for a given time point only.