The power calculations are based on clinically interesting differences in percentage of neutrophils and spirometry values. The study is designed to include at least 20 participants in each group based on a power estimate of 90%, which assumes a 95% significance level, to detect a true difference in the percentage neutrophils between two tests of at least 16%. Power calculation for FEV1 and FVC% of predicted: if the goal is to detect a difference of 1.5% in FEV1 and FVC% predicted, then given a standard deviation of 5% the sample must consist of 117 persons in each group. This will ensure 90% power to detect a difference at the 5% significance level.