Growing up on an Amish Farm Protects Children Against Asthma, UAHS Collaborative Research Shows
http://memo.ahsc.arizona.edu/index.cfm/memos/view/26804/bf9c4312ce62220a
Barnyard Dust Offers a Clue to Stopping Asthma in Children
http://www.nytimes.com/2016/08/04/health/dust-asthma-children.html