The effects of ozone and nitrogen dioxide on lung function in healthy and asthmatic adolescents.

The aim of this project was to investigate whether or not well characterized groups of healthy adolescents and adolescents with asthma differed in their sensitivity to ozone and nitrogen dioxide at near ambient concentrations of these pollutants. The project was divided into three phases. In each phase, ten healthy and ten asthmatic adolescents were exposed via a mouthpiece to three different atmospheres (filtered air, ozone, and nitrogen dioxide, at either 0.12 or 0.18 ppm) on separate days at least one week apart. During Phase I, subjects at rest inhaled the test atmospheres at 0.12 ppm for two 30-minute periods. The following pulmonary functional values were measured before, during, and after exposure: peak flow, total respiratory resistance, thoracic gas volume at functional residual capacity, maximal flow at 50 and 75 percent of expired vital capacity (performed with both room air and a helium-oxygen mixture), and forced expiratory volume in one second. Pulmonary function was not consistently altered in either the asthmatic or the healthy nonasthmatic adolescents as a result of the exposures. As a result, the study was repeated with the addition of ten minutes of exercise to the 30-minute rest exposure period (Phase II). In Phase II, small but significant increases in total respiratory resistance to all test atmospheres were seen after exposure at 0.12 ppm during exercise in both healthy and asthmatic adolescents. However, the increase in resistance between the groups of subjects was not statistically different. On the basis of these results, Phase III was conducted at higher concentrations of the pollutants (0.18 ppm). In Phase III, statistically significant changes were seen in average total respiratory resistance values in both healthy and asthmatic adolescents exposed to 0.18 ppm ozone while exercising. Again, the difference between the groups was not significant. Small decreases in average forced expiratory volume were found in healthy subjects exposed to ozone and filtered air. After exposure to nitrogen dioxide there was a 3 percent decrease in the forced expiratory volume in one second in asthmatic subjects. This change was not significant. It is concluded that there were no differences in pulmonary function responses between asymptomatic, allergic asthmatic adolescents and healthy adolescents exposed to either ozone or nitrogen dioxide under the conditions of these studies. However, an increase in total respiratory resistance was observed in both asthmatic and healthy adolescent subjects after their exercise exposure to 0.18 ppm ozone.(ABSTRACT TRUNCATED AT 400 WORDS)