If we exclude Central London and talk about Zone 2 outwards, anecdotally I'd say it is purely based on knowing the makeup of certain neighbourhoods.

Removed from that though, you only need to make a few assumptions to come to the conclusion it would be anyway.

If we assume, say, that people would prefer to live on a side street over a main road, and then away from a junction rather than on a junction, from that it stems that it's going to be cheaper to own/rent a place in the most polluted areas.

There are differences in income and wealth by race.