Compile a list of research related to Air Quality, health, and environmental justice

There will be no shortage of research on the topic of air quality as it relates to health outcomes and environmental justice, so this will be a living document. Let's generate a markdown or text file and place it in the `docs` folder. 

It might be worth adding resources like the ALA's [State of the Air report](https://www.lung.org/research/sota/key-findings). 