Abstract
The pathological study of pulmonary resp onse in rats was iesnoras done by light and electron microscopies after continuous exposure to either 0.1 ppm ozone (03) or a mixture of 0.1 ppm 03 and 0.3 ppm nitrogen dioxide (NO2) for 1, 3, 6 and 18 months.
After 1-month exposure to 03, hypertrophy and proliferation of Type 2 cells, enhanced permeability of capillary endothelial cells and slight edema in pulmonary interstitial connective tissue were observed. After 3-month exposure, edema became more evident, but it subsided gradually as the exposure lasted for 6 and 18 months.
The changes by combined exposure to 03 and NO2 at the interstitial connective tissue appeared to be somewhat more marked than those caused by exposure to 03 alone. The edema of pulmonary connective tissue became progressively pronounced as the exposure lasted.
