Changes in FEV1 (A) and FVC (B) after Day 1 pollutant exposures. Subjects performed pre-exposure spirometry immediately before a 2 hr exposure (filtered air, O3, DE, or DE + O3). Spirometry was performed immediately post-exposure and every hour post-exposure for 4 hr. FVC Data in (B) derived from the immediately post time point only. Data in the figure are presented as the mean ± SEM of each group at that time point. *p < 0.05 vs air exposed; **p < 0.05 vs O3 exposure alone; ‡ p = 0.057 vs the sum of the O3 plus DE exposure FEV1 changes using Mixed Effects Model testing as described in the materials and methods section.