Fig. 2

Of the 74 volunteers that were screened 19 subjects were excluded due to insufficient sputum samples. Of these 10 subjects did not produce a sufficient amount of cells to perform all required analysis (<200.000 cells) and 9 subjects showed a percentage of >50 % neutrophils in their sputum, which was chosen as a cut-off point to allow a sufficient increase after ozone exposure. ^a15 subjects crossed over from the 5.5 mg group, an additional 5 subjects were included directly. N = number of subjects