EMS structure in urban areas varies to fit the need of the community. It is often part of the Fire Department – but may be a third service separate from police and fire – or follow a public utility model privately contracted to provide EMS services. In more suburban and rural areas EMS often follows a fourth model, with volunteers providing part or all of the EMS care in that county. Responding to emergencies within an airport is a unique challenge that does not fit a traditional model of any kind and carries with it the need for a special response team. During 2017, the Nashville International Airport (BNA) saw 13.5 million passengers pass through its gates. With this influx of travelers comes a wide variety of associated medical emergencies and the need for rapid response. From 2016 to 2018, there was an average of 512 medical emergencies per year at BNA.