The effect of age on the ozone-induced pulmonary edema and tolerance in rats.

Effects of the age on the lung injury caused by ozone and on the development of ozone tolerance were examined in male rats by measuring pulmonary weight response. The pulmonary susceptibility to ozone was found to be proportional to the logarithm of body weight from 70 to 300 g, but extraordinarily enhanced beyond 300 g (about 9 weeks old). The developmental process of ozone tolerance in young rats were found to be similar to that in young adults, but apparently different from that in older rats. Pulmonary ability to induce ozone tolerance was higher in young rats weighing less than 300 g than in older rats. These results suggest that the rat lung response to ozone alters as the rats grow older beyond 9 weeks.