Relation of pulmonary responses induced by 6.6-h exposures to 0.08 ppm ozone and 2-h exposures to 0.30 ppm ozone via chamber and face-mask inhalation

While direct comparison of pulmonary responses to 6.6-h exposures to 0.08 to 0.12 ppm ozone (O-3) have demonstrated that chamber and face-mask inhalation methods yield closely similar results, no comparative study of responses to 2-h intermittent exercise (IE) exposures to higher O-3 concentrations have been reported. The present study was designed to achieve three primary objectives: (1) to compare pulmonary function and symptoms effects of a 2-h IE exposure to 0.30 ppm O-3 via chamber and via face mask; (2) to compare the pulmonary effects of 6.6-h chamber exposure to 0.08 ppm O-3 to those observed in 2-h IE 0.30 ppm O-3 exposures via chamber and via face mask; and (3) to examine filtered air (FA) recovery pulmonary and symptoms responses following chamber exposures of 6.6 h to 0.08 ppm O-3 and 2 h to 0.30 ppm O-3. A simple regression of post-exposure percent change in FEV1.0 for the 2-h IE, 0.30-ppm O-3 chamber exposure as a function of post-exposure percent change in FEV1.0 for the 2-h IE, 0.30-ppm O-3 exposure with face mask yielded an R-2 of .83. Further, a regression of the postexposure FEV1.0 response to the chamber 6.6-h, 0.08-ppm O-3 exposure as a function of postexposure FEV1.0 response to the face mask 2-h IE, 0.30-ppm O-3 exposure (R-2 of .34) was similar to the .40 value obtained for the two chamber exposures FEV1.0 response comparison. Results of the 1.4-h FA recovery following the two chamber O-3 exposures showed different rates of FEV1.0 and symptoms rectification that appeared related to the total O-3 dose ( product of O-3 concentration, ventilation rate, and duration). More data are needed to clarify short-term recovery of O-3-induced pulmonary effects and how they may be related to the more abundant data available on the delayed recovery of pulmonary function seen over longer time periods, such as 24 h.