On December 19, 1997, at 1815 hours Pacific standard time, the crew of an Alaska Airlines MD-80, N932AS, operating as Flight 536 from Palm Springs, California, to San Francisco, California, under 14 CFR Part 121, ordered an emergency evacuation after experiencing noxious fumes entering the aircraft. Visual meteorological conditions existed at the time. There was no damage to the aircraft and no injuries to the 5 crewmembers or to the 69 passengers. According to the operator, the aircraft was taxiing to the gate after landing when fumes and mist began to enter the cabin through the air conditioning ducts. Although first noted as thin, the vapors quickly filled the cabin, reducing visibility, and causing respiratory distress along with burning eyes to crew and passengers. The crew elected to stop the aircraft on the taxiway near the intersection of "A" and "H" taxiways. The captain ordered an immediate evacuation over the aircraft's public address system. The crew estimated the evacuation was accomplished within 90 seconds. After the evacuation, the flight attendants commented on having to divest passengers of carry-on baggage during the evacuation. A concern was that the baggage taken from the passengers could block the path to the exit(s). All flight attendants commented on how useful they found their flashlights to be. All retrieved their flashlights before proceeding to the exits and found them to be invaluable during the evacuation, as well as on the ground. Subsequent investigation revealed the source of the vapors as a failed hydraulic return line from the left-hand engine thrust reverser. Leaking fluid from the line was ingested into the aircraft's APU that had been started by the flight crew after landing in accordance with normal procedures.