> those most affected are the poorest
Please pardon my pedantry but this is by definition what poor is : having less means to escape material woes. Rich people are the ones that can elect to live in healthy areas.
Yes, but if the air pollution we're talking about is invisible then why would the rich elect for less exposure? Some might look at air quality data, but I suspect what is really going on is they seek out quiet. Noise pollution is the thing people really hate and avoiding that will likely lead to getting better air quality too.
In many cities a lot of rich people live in the city centre. London is an example. Take a look at house prices and rents in Westminster or the City, or even adjoining areas. The only poor people there are the ones in social housing who are a minority.