Comparison of Chamber and Face Mask 6.6-Hour Exposure to 0.08 ppm Ozone Via Square-Wave and Triangular Profiles on Pulmonary Responses
Author: Adams, William C.
Source: Inhalation Toxicology, Volume 15, Number 3, 1 March 2003 , pp. 265-281(17)
Publisher: Informa Healthcare
Abstract:Recently, a stainless-steel air pollution chamber was acquired in this laboratory, and data were obtained in a study that convincingly demonstrated that chamber and face-mask inhalation methods of exposing young adult subjects for 6.6 h to nearly identical total inhaled O3 doses at 0.12 ppm produced very similar pulmonary function, symptoms, and exercise ventilatory pattern responses. However, the results of a 6.6-h face-mask exposure to 0.08 ppm O3, compared to some previous chamber exposure study results, revealed several small incongruities that may be due primarily to high individual subject "noise" in responses to a relatively low O3 exposure. To resolve these differences, it was the primary purpose of this study to compare chamber exposure responses to those elicited via face-mask exposure to 0.08 ppm O3 for 6.6 h with subjects serving as their own controls. Two types of O3 exposure patterns were used: (1) the usual square-wave profile, and (2) an acute triangular profile, in which O3 concentration was increased each hour from 0.03 ppm to 0.15 ppm during h 4 and then decreased each hour to 0.05 ppm (mean = 0.08 ppm). Thirty young adults (15 of each gender) served as subjects. The two exposure methods (i.e., face mask and chamber) yielded near identical total inhaled O3 doses in both the square-wave and triangular exposure profiles, and produced very similar postexposure pulmonary function, symptoms, and exercise ventilatory pattern responses. However, pulmonary function and symptoms responses became statistically significant from preexposure at the end of h 4 (when [O3] = 0.15 ppm) in the triangular protocols, but not until h 6 in the square-wave protocols. These results support previous evidence that O3 concentration has a greater singular effect in the total inhaled O3 dose than do VE and exposure duration.
Document Type: Research Article
Affiliations: Human Performance Laboratory, Exercise Biology Program, University of California, Davis, California, USA
Publication date: March 1, 2003