Trains, planes, and automobiles weren't enough for these people, so they moved on the cows, and farms and now it's the tree's turn.
Trees Have Become a Hidden Source of Air Pollution in Los Angeles
https://www.sciencealert.com/trees-have-become-a-hidden-source-of-air-pollution-in-los-angeles
Trees Have Become a Hidden Source of Air Pollution in Los Angeles
https://www.sciencealert.com/trees-have-become-a-hidden-source-of-air-pollution-in-los-angeles