Sixty-day old, male rats were exposed to air, 0.5 or 1.5 ml/1 fog-oil for 3.5 hr/d, 4 days/wk for either 4 or 13 wk. Following the acute (4 wk) exposure to 1.5 mg/1, a multifocal pneumonitis was observed. Lung lavage fluid had an elevated number of polymorphonuclear leukocytes, alveolar macrophages, total cells and an increase in lavage fluid protein. Lung wet and dry weights were increased. A lesser increase in the number of alveolar macrophages and lung weights was observed after exposure to 0.5 mg/1. Pulmonary function tests revealed an increase in end expiratory volume (EEV) in animals exposed to 1.5 mg/1. A decrease in zoxazolamine-induced paralysis time was observed following both 0.5 and 1.5 mg/1, however, no effect on pentobarbital-induced sleep time was observed. The subchronic (13 wk) exposures resulted in decreased body weight and increased lung dry weights at both 0.5 and 1.5 mg/1, an increase in lavage fluid protein and EEV following exposure to the 1.5 mg/1 concentration. Zoxazolamine paralysis time, which was decreased after both concentrations, correlated with an increase in aryl hydroxylhydrolase (AHH) activity in the liver. In conclusion, it appears that inhalation of smoke SGF-2 causes minimal pulmonary and systemic effects.