"Uniform Materials Affect Flight Attendant
Safety and Ability to Help Passengers
Evacuate Burning Aircraft
The primary duty of a flight attendant is to help passengers evacuate the aircraft in an emergency requiring evacuation. If a flight attendant is incapacitated, that duty cannot be accomplished. In an emergency, particularly one involving fire, the flight attendant’s uniform can affect his or her ability to help passengers evacuate an aircraft.
“Safety experts agree that in order to decrease the chance of sustaining burns, it is better to wear long sleeves and pants, than it is to wear short sleeves and short pants. In addition, [natural] fabrics such as wool and cotton are better than synthetic fabrics. Also, it is better to have low-heel shoes which are enclosed, and straps or laces are encouraged while sandals are discouraged.”"
Flight Safety Foundation - Cabin Crew Safety
http://www.flightsafety.org/ccs/ccs_mar_apr99.pdf