Please annotate the 3 following sources for a paper on the causes, effects, and solutions to air pollution:

1) https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0216550
2) https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0194364
3) https://www.atsjournals.org/doi/full/10.1164/ajrccm.162.supplement_1.maic-12