alt Hacker NewsThe localisation of it struck me when I read an Irish EPA report on traffic-related air pollution a few years ago that recommended carrying your child if you were walking regularly near heavy traffic. The air at 0.8m (their breathing height) has 5-15% more NOx in it than the air at 2m (the height they would breath at being carried by you).
I remember reading something similar about walking on the part of the pavement furthest from the road, because being an extra meter or so away makes a big difference