Ozone exposure aggravates asthma, as has been demonstrated in both controlled exposures and epidemiologic studies. In the current double-blind crossover study, the authors evaluated the effects of dietary antioxidants (i.e., 400 IU vitamin E/500 mg vitamin C) on ozone-induced bronchial hyperresponsiveness in adult subjects with asthma. Seventeen subjects were exposed to 0.12 ppm of ozone or to air for 45 min during intermittent moderate exercise. Bronchial hyperresponsiveness was assessed with 10-min sulfur dioxide (i.e., 0.10 ppm and 0.25 ppm) inhalation challenges. Subjects who were given dietary antioxidants responded less severely to sulfur dioxide challenge than subjects given a placebo (i.e., forced expiratory volume in the 1st sec: -1.2% vs. 4.4%, respectively; peak flow: +2.2% vs. -3.0%, respectively; and mid-forced expiratory flow: +2.0% vs. -4.3%, respectively). Effects were more pronounced when subjects were grouped by response to sulfur dioxide at the screening visit. The results suggest that dietary supplementation with vitamins E and C benefits asthmatic adults who are exposed to air pollutants.

Adult↗

PubMedDate not supplied

Effects of inhaled sulfur dioxide (SO2) on pulmonary function in healthy adolescents: exposure to SO2 alone or SO2 + sodium chloride droplet aerosol during rest and exercise.

Recently we reported statistically significant changes in pulmonary functional measurements in asthmatic adolescents exposed at rest or during exercise. To demonstrate whether those results were due to the subjects' adolescence, or more likely, to their diagnosis of asthma, we repeated identical exposures in healthy adolescents. The changes after exposure to sulfur dioxide (SO2); however the changes were only slightly greater than those seen after sham exposure. After exposure at rest to 1.0 ppm SO2 + 1 mg/m3 sodium chloride (NaCl) droplet aerosol, the healthy adolescents showed small (3%) but statistically significant reductions in forced expiratory volume in one second (FEV1.0). No significant changes were seen following exposure to NaCl of SO2 alone at rest. Exposure to the SO2 modes during moderate exercise produced greater changes. Following exposure to either the SO2 + NaCl mixture or 1.0 ppm of SO2 alone, the reductions in FEV1.0 were slightly greater (6%) and prolonged compared with those seen at rest. Significant decreases also were seen in Vmax50 and Vmax75. A small decrease (4%) in FEV1.0 was seen following exposure to NaCl alone during exercise, but the change was not statistically significant. The changes seen in the healthy adolescents were slight compared to those seen in the asthmatic adolescents previously exposed (changes of 23-67%). We conclude that asthmatic adolescents are much more sensitive to the effects of inhaled SO2 than are healthy adolescents.

Adolescent↗

PubMedDate not supplied

Respiratory effects of inhaled sulfuric acid on senior asthmatics and nonasthmatics.

The objective of this study was two-fold: (1) to investigate the response of asthmatic subjects who were 60 to 75 y of age to inhaled sulfuric acid, and (2) to compare that response to findings from healthy subjects in the same age group. Nine subjects who had asthma and eight healthy subjects participated. Each subject was exposed to clean air, an inert ammonium sulfate aerosol, or 70 micrograms/m3 sulfuric acid during a 40-min exposure period composed of 30 min at rest and 10 min of light exercise on a treadmill. The sulfuric acid was delivered twice, one preceded by a lemonade drink to neutralize oral concentrations of ammonia. Exposures were separated by at least 1 wk. Oral ammonia levels and pulmonary function parameters (forced expiratory volume in one second, forced vital capacity, and total respiratory resistance) were measured before and after each exposure. None of the functional parameters in either group showed significant changes. However, total respiratory resistance changes from baseline after sulfuric acid exposure were significantly higher (+16%) in the asthmatic subjects, compared with the healthy subjects (-6%). These data suggest that older subjects are not at increased risk for adverse respiratory effects from inhalation of sulfuric acid by virtue of age alone, and older subjects with asthma are slightly more vulnerable than are their healthy peers.

Adolescent↗

PubMedDate not supplied

The effect of duration of exposure on sulfuric acid-induced pulmonary function changes in asthmatic adolescent subjects: a dose-response study.

To evaluate the pulmonary effects of varying doses of sulfuric acid, adolescent subjects with asthma were exposed to 35 or 70 micrograms/m3 sulfuric acid for 45 or 90 min. Exposure was carried out during intermittent moderate exercise. The pulmonary functions measured before and after exposure were FEV1, FVC, and total respiratory resistance. The 45 min exposures were associated with larger decreases in FEV1 (-6% or -3%) than the 90 min exposures (-1% or +2%). Analysis of variance of the change in FEV1 among the exposures revealed that the 45 min exposure to 35 micrograms/m3 was significant (p = 0.03). The p value for 45 min exposure to 70 micrograms/m3 was not significant (p = 0.08). Using analysis of variance, neither of the 90 min exposures was associated with a significant decrease in FEV1 compared to air exposure. Also, none of the changes in FVC or RT was significant. When baseline to post-exposure changes were compared for each of the five test atmospheres using paired t tests, both of the 45 min exposures were associated with statistical significance (p < 0.001 for 35 micrograms/m3 and p < 0.005 for 70 micrograms/m3). This baseline to post exposure change was not statistically significant for the 90 min exposures. The reason for the lesser effect on pulmonary function at increased exposure duration is not known; it may be due to changes in either varying deposition patterns or changes in buffering capacity of the cells lining the airways. With respect to individual sensitivities to H2SO4, the data showed a significant consistency across test atmospheres.

Adolescent↗