Inflammatory effects of ozone in the upper airways of subjects with asthma

The objective of this study was to determine whether exposure to ozone causes inflammatory or functional changes in the upper or lower airways of asthmatic and nonasthmatic individuals. Ten asthmatic and eight nonasthmatic subjects were exposed to clean air, 120 ppb ozone, or 240 ppb ozone for 90 min during intermittent moderate exercise using a head dome exposure system. Pulmonary function tests, posterior rhinomanometry, and nasal lavage were performed before and after exposure. Leukocyte counts and chemotactic factors leukotriene B4 (LTB4), platelet-activating factor (PAF), and interleukin-8 (IL-8) were analyzed from nasal lavage fluid. In subjects with asthma, a significant increase (p < 0.05) in the number of white blood cells in lavage fluid was detected both immediately and 24 h after exposure to 240 ppb ozone, as was a significant increase in epithelial cells immediately after exposure (p < 0.05). No significant cellular changes were seen in nonasthmatic subjects. A significant correlation was observed between IL-8 and white blood cells counts after exposure to 240 ppb ozone (r = 0.76) in asthmatic subjects. No significant changes in pulmonary or nasal function or biochemical mediators were found in either the asthmatic or nonasthmatic subjects. These data indicate that asthmatic individuals are more sensitive to the acute inflammatory effects of ozone than nonasthmatic individuals.