To assess the early cellular inflammatory response of the lungs, 7 rats per group were exposed nose-only to 13 mg/m 3 of chrysotile asbestos, 7 h/day for 2, 4, or 6 wk. Lung histopathology and bronchoalveolar lavage (BAL) were analyzed. In exposed animals, dose-related bronchiolitis and fibrosis were found that were not seen in control rats (p < 0.001