Consequences of Prolonged Inhalation of Ozone on F344/N Rats: Collaborative Studies. Part V: Effects on Pulmonary Function

Research Report 65-V, November 1994

Ozone is the major pollutant in smog. It is formed by complex photochemical reactions between nitrogen oxides and volatile organic compounds in the presence of sunlight. Motor vehicle and industrial emissions are prominent sources of these compounds. Peak atmospheric ozone concentrations generally occur during the summer months because the photochemical reactions that produce ozone are enhanced by sunlight and high temperature. HEI-funded investigators studied whether long-term ozone exposure causes or enhances alterations that are characteristic of chronic lung diseases, such as fibrosis or emphysema, in the lungs of laboratory animals. Drs. Harkema and Mauderly at the Lovelace Biomedical and Environmental Research Institute exposed 65 male and female F344/N rats to either 0.12 ppm, 0.5 ppm, or 1.0 ppm ozone for 7 hours/day, 5 days/week, for 20 months, and investigated the effects of this exposure on lung function. The investigators\' goal was to characterize the nature and magnitude of pulmonary impairment that may be associated with chronic exposure to ozone. The availability of benchmark data on pulmonary function in this rat cohort was considered to be essential to the overall interpretation of the other seven NTP/HEI studies