I think you're misinterpreting my comment; I'm not stating that the majority of social housing is located in high pollution areas but rather that some of it is

I think you're misinterpreting my comment; I'm not stating that the majority of social housing is located in high pollution areas but rather that some of it is (a decent amount). These people are effectively in a sort of rent-control style scenario in which moving out and in to privately rented accommodation might mean doubling the rent and moving from a stable long-term tenancy to a yearly thing. They technically have the ability to move whilst being heavily discouraged from doing so. This is quite different to, for example, someone who owns or rents a house that costs 25% more than an equivalent one in a side street, say. It's more of a cost benefit analysis for them. There is however the issue still that eventually, someone is going to end up living there, because housing in London isn't going to be left empty if it exists.