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OZONE UPTAKE IN THE INTACT HUMAN RESPIRATORY TRACT - RELATIONSHIP BETWEEN INHALED AND ACTUAL DOSE
Citation:
Rigas, M L., S. N. Catlin, A. BenJebria, AND J. S. Ultman. OZONE UPTAKE IN THE INTACT HUMAN RESPIRATORY TRACT - RELATIONSHIP BETWEEN INHALED AND ACTUAL DOSE. JOURNAL OF APPLIED PHYSIOLOGY 88(6):2015-2022, (2000).
Description:
Inhaled concentration (C), minute volume (MV), and exposure duration (T) are factors that may affect the uptake of ozone (03) within the respiratory tract. Ten healthy adult nonsmokers participated in four sessions, inhaling 0.2 or 0.4 ppm 03 through an oral mask while exercising continuously to elicit a MV of 201/min for 60 min or 401/min for 30 min. In each session, fractional absorption (FA) was determined on a breath-by-breath basis as the ratio of O3 uptake to the inhaled 03 dose. The mean plus/minus SD value of FA for all breaths was 0.86 plus/minus 0.06. Although C, MV, and T all had statistically significant effects on FA (P < 0.0001, P = 0.004, and P = 0.026, respectively), the magnitudes of these effects were small compared with intersubject variability. For an average subject, a 0.05 change in FA would require that C change by 1.3 ppm, MV change by 46 1/min, or T change by 1.7 h. It is concluded that inhaled dose is a reasonable surrogate for the actual dose delivered to a particular subject during 03 exposures of <2 h, but it is not a reasonable surrogate when comparisons are made between individuals.
The U.S. Environmental Protection Agency through its Office of Research and Development collaborated in the research described here. This research has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use. This work has been partially funded by National Institute of Environmental Health Sciences research grant R01 ES-06075. Clinical support was provided by the General Clinical Research Center of the Pennsylvania State University through funding by National Center for Research Resources grant M01 RR-10732.