Skytrax's World Airport Awards are based on 12.1 million survey questionnaires filled out by passengers covering 108 different nationalities and 395 airports worldwide during a nine-month survey period in 2012 and 2013.

CNN: U.S. airports don't stack up

The findings, published in the New England Journal of Medicine, come from 60, 290 questionnaires filled out by women in the Nurses' Health Study, a survey of more than 121, 000 female registered nurses begun in 1976.

BBC: Exercise reduces gallstone risk