Abstract
The pulmonary responses to components of acid fogs, nitric acid, sulfuric acid, and hydroxymethanesulfonate (HMSA), in combination with ozone (O3) were measured to determine if the acid components altered the course of inflammatory responses to the oxidant. Rats were exposed 4 h to 0.4 ppm O3 0.4 ppm O3 + 0.7 mg/m3 HNO3 + 0.6 mg/m3 H2SO4 0.6 mg/m3 HMSA, and 0.4 ppm O3 + 0.5 mg/m3 HMSA. Breathing pattern and metabolic rate were measured during exposure, and fatty acid composition of pulmonary surfactant (PS), nasal epithelial injury, oxidant-induced lung parenchymal lesions, and changes in the total protein in the lavage fluids were measured 23–48 h postexposure. Ozone alone affected all measures except nasal epithelial injury, and the presence of inorganic acids or HMSA in combination with 0.4 ppm O3 did not significantly modify the response to O3 alone. The only response to 0.6 mg/m3 HMSA alone was depression in metabolic rate during exposure. The presence of a pulmonary irritant rapid-shallow breathing pattern during exposure to O3 was associated with development of postexposure inflammatory effects including changes in PS fatty acid composition, increase in lavage fluid protein, and development of lung parenchymal lesions, suggesting that pulmonary function changes can predict changes in histological and biochemical events of the postexposure inflammatory response to O3 inhalation.