[sundvor]

Yes, I researched this for evaluating my son's previous school - there's a sharp drop off even from the 10-20-30 metre range to the 100-150 metre one, and things like wind directions certainly matter.

AusGov in their infinite wisdom built this primary school right on top of one of the busiest Melbourne streets for east-west through traffic, with long periods of bumper-to-bumper including the heavy trucks which are the worst. (You'd think cars in Aus have bad standards, but then there's the trucks.)

I'm willing to bet no-one even cared, as evidenced by the complete lack of air purifiers in the classrooms.