Inhaled atmospheric pollutants in the genesis of pulmonary abnormalities.

Abstract

Groups of animals were given two-hr acute exposure to high (200 ppM for rabbits, 150 ppM for rats), moderate (100 ppM for rabbits, 75 to 80 ppM for rats and guinea pigs) or low (25 ppM for rabbits, 15 to 20 ppM for rats and guinea pigs) doses of NO/sub 2/. The high dose killed all rats and 33% of the rabbits within 24 hr (edema). All survived the moderate dose with some edema, inflammatory exudate, and epithelial degeneration and regeneration after 24 hr, and progressive repair including macrophage infiltration, until almost complete repair by 2 weeks. There was some repair in low-dose animals but proportionally less initial damage. Multiple (2 hr/day for 5 days) low-dose exposures resulted in less severe inflammation and repair within about 7 days. Respiratory bronchioles were most severely affected.