Many studies (Dales et al., 2009, 2008; Holguin et al., 2007) have
used traffic density to assess risk of developing respiratory symptoms
in children, but did not find relationships with ventilatory
lung function measurements such as FVC or FEV1. Comparing the
latter two studies (i.e., Dales et al. (2008) and Cakmak et al. (2012))
reveals that traffic counts may be a better representation of exposure
effects to the magnitude of traffic than road density (or traffic
density), yet effect modification by socioeconomics were not
addressed. The present study provides further evidence that traffic
counts can effectively represent traffic exposure and that this association
is significant in those with lower education.