Scared of flying? Here’s one more reason you can add to your list. There is concern about the microbiology is airplane cabins, as it is a closed environment utilizing recycled air. The occupant density is much greater than normal “built” environments, and passengers cannot leave when they want to. But not much is known about the diversity of these microbes. Samples were collected from various domestic and international flights at different times and sequenced. Domestic flights tended to experience a decrease in the number of biological agents over time, whereas international flights did not show as drastic of a decrease. This study found that there is a wide range of microbes that can be found on commercial flights than previously known.