perhaps the disadvantage is that, over time, living nearest to traffic _is_ the disadvantage, as it means living most immediately near pollution concentration.

Sincere reply assuming sincere question, the implication is that they are statistically much more likely to live near interstates and highways. Since historically land owned by poor 'disadvantaged groups' has been easier for state and federal governments to get their hands on.

The sentence, while poorly written, isn't saying that "health impacts don't matter for 'non-disadvantaged people'". A reading that is disingenuous.

I see. In the areas familiar to the authors, disadvantaged groups typically live closer to the source of the pollution.

Makes sense now. Thanks.

Also disadvantaged groups might consume less healthcare and might be less aware of air quality, etc. and so may be more likely to have bad health outcomes for given environmental inputs.