Children breathe faster than adults and their are still developing.
They also stand closer to the pipes of passing traffic.
Studies in several cities link roadside to slower lung growth.
The effect appears strongest for schools within a hundred metres of a main road.
Cleaning the whole air basin is slow and expensive work.
Protecting a single school gate is neither.
Closing the street to cars at opening and closing time cuts sharply.
between the pavement and the road trap a measurable share of particles.
Moving the entrance to a quieter side of the building helps as much as either.
at child height give parents evidence rather than impressions.
Once a number exists, it is difficult for an authority to ignore.
None of this substitutes for cleaner vehicles across the city.
It does, however, protect one cohort of children while the larger work proceeds.