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Pulmonary Responses in Healthy Young Adults Exposed to Low Concentration of Ozone for 6.6 Hours with Mild Exercise
Citation:
KIM, C. S., H. R. KEHRL, A. G. RAPPOLD, J. Brown, R. B. DEVLIN, D. DIAZ SANCHEZ, AND M. HAZUCHA. Pulmonary Responses in Healthy Young Adults Exposed to Low Concentration of Ozone for 6.6 Hours with Mild Exercise. Presented at American Thoracic Society Annual meeting, New Orleans, LA, May 14 - 19, 2010.
Impact/Purpose:
abstract for an annual meeting
Description:
Rational: Recent studies have shown small but significant decreases in lung function following a prolonged exposure (6.6 hour) of healthy young adults to levels of ozone (0.08 ppm) near the current 8 hour standard. It is unclear, however, if such effects may be extended to concentrations below 0.08 ppm. In order to answer the question, we have been conducting a study designed for a large number of subjects (N=60). The purpose of this report is to present the interim data consisting of 30 subjects and to compare the results with earlier comparable studies. Methods: A group of 30 healthy young adults (men and women in equal number, age = 18-35 years) was exposed to 0.0 (filtered air), 0.06 and 0.08 ppm ozone for 6.6 hours with moderate exercise in a tightly controlled environmental chamber. Spirometric lung function (e.g., FEV 1 and FVC) was measured and scores of each of four symptoms (in the scale of 0-4) were recorded immediately before, during and after exposure. Changes in lung function and symptom scores with ozone exposures were compared with those with filtered air exposure. Pre-and post-exposure results were compared by paired t-tests and time-course changes were analyzed by l-way or 2-way ANOVA with repeated measures with significance at p=0.05. Results: The post-exposure FEV1 decrement adjusted by filtered air was 1.91(+/-0.9 SE) and 3.42% (+/-1.0 SE) for 0.06 and 0.08 ppm ozone, respectively (both p<0.05). The FVC decrement was 1.34 (+/-0.70 SE, p=0.07) and 2.39% (+/-0.79SE, p<0.05) for 0.06 and 0.08 ppm ozone, respectively. Individual variability in % change in FEV1 after ozone exposure is mostly within +/-5% for both filtered air and 0.06 ppm and from +5% to -10% for 0.08 ppm. Individual variability was smaller in FVC than FEV l. There were no differences in both FEV 1 and FVC responses for males vs. females. Symptom scores were low most of time. Mean symptom score was greater vs. filtered air only after completion of 0.08 ppm exposure. Conclusions: Exposure to 0.08 ppm ozone for a prolonged period of time causes small but measurable decrement of spirometric lung function consistent with earlier studies. Although the absolute values are small, lung function decrement may be extended to 0.06 ppm exposure. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.