Effects of nitrogen dioxide on pulmonary cell population.

Studies from this laboratory have shown that ozone produces changes in the number and function of cells obtained by pulmonary lavage. In similar experiments, rabbits exposed to levels of NO(2) from ambient to 60 ppm demonstrated increased numbers of polymorphonuclear leukocytes in the lung washings. This phenomenon persisted for more than 72 hr after a single 3-hr exposure. When streptococci were instilled in the lungs of NO(2)-exposed anesthetized rabbits 30 min before lavage, a pronounced inhibition of phagocytic activity was observed. With these criteria, NO(2) appeared less effective than ozone as a pulmonary irritant.