Minute Suites started operating 13 pods at Philadelphia International Airport in late 2009 and five at the Hartsfield-Jackson Atlanta International Airport in 2011.

BBC: Sleep in a pod on the fly

Through the end of November, Hartsfield-Jackson Atlanta International Airport led the nation with 80 guns found.

CNN: Airport screeners discover more than 1,500 guns in 2012

Though Hartsfield-Jackson Atlanta International Airport ranks first in the number of flights, it was eighth on the researchers' list of potential disease spreaders.

CNN: Researchers list top 10 airports for spreading disease