Addendum

Re: Riley S, Wallace J, Nair P. Proximity to major roadways is a risk factor for airway hyper-responsiveness in adults. Can Respir J 2012;2:89–96.

The authors of this study acknowledge Dr Chris Allen for constructing the methacholine database at the Firestone Institute for Respiratory Health, and the Hamilton Community Foundation for providing the investigators a Community Health Education and Research Fund to conduct this study.