Statistical analysis
Subjects acted as their own controls, and comparison of post-air exposure and post-diesel exhaust exposure were performed using Wilcoxon’s nonparametric signed-rank test. A p value of 0.05, or less, was considered significant and data are presented as median and interquartile range. Correlation analyses were carried out using Spearman’s rank order correlation with a p value of 0.05, or less, was considered significant. Comparisons were performed using absolute value in a given parameter after air or diesel exposure. Comparisons of the change in a given parameter were performed using (post-diesel value minus post-air value). All statistical analyses were performed using SPSS version 27.0 (SPSS Inc., Chicago, USA). Graphical presentation of absolute value in a given parameter after air and diesel for each subject were performed using GraphPad software, prism version 9 (San Diego, CA, USA).