Cowie CT, Ezz W, Xuan W, et al. A randomised cross-over cohort study of exposure to emissions from a road tunnel ventilation stack. BMJ Open 2012;2:e001201. Spacing in table 3 was inaccurate and missed some header rows. The corrected table is below. Also, in the third paragraph of the section entitled “Health outcomes” the sentence “... higher scores for EYE, CHEST and THROAT symptoms (last row, table 3)” should actually be “higher scores for EYE and CHEST symptoms (table 3).” In addition, the volume number should be listed as “2” in this article. We apologise for these errors.