Why do you assume that fine particulate is at the highest in city centers? It's often higher than average, but the highest is frequently outside of the city cen

Why do you assume that fine particulate is at the highest in city centers? It's often higher than average, but the highest is frequently outside of the city center, where highways have been constructed through pre-existing, poorer neighborhoods. The South Bronx is the famous example of this[1]. [1]: https://www.theguardian.com/us-news/2019/apr/04/new-york-south-bronx-minorities-pollution-inequity https://www.theguardian.com/us-news/2019/apr/04/new-york-sou...