Respiratory bronchiolitis following long-term ozone exposure in bonnet monkeys: a morphometric study.

To quantitate the response of respiratory bronchiolar (RB) epithelium and peribronchiolar connective tissue (PCT) to chronic exposure to high ambient levels of ozone, two groups of 8 adult male bonnet monkeys each were subjected 8 h daily for one year to 0.64 ppm (UV standard) ozone or filtered air, respectively. Blocks of tissue selected throughout the lung and from first generation RBs following airway microdissection had the following significant exposure-related changes: 57% greater volume of RB in the lung, 27% smaller diameter of RB lumen, 179% thicker media and intima of peribronchiolar arterioles, 61% thicker RB epithelium, and 77% thicker PCT.