Eighty passengers on a Frontier Airlines (search) plane coming from Philadelphia were quarantined Tuesday for more than 90 minutes at Denver International Airport (search) after a woman became ill on the flight.

An in-flight medical consulting firm used by the airline was unable to determine the woman's ailment and a medical team that met the plane on the tarmac kept passengers on Flight 449 as a precaution, airline spokesman Joe Hodas said.

Passengers were allowed off the Airbus A319 at 9:55 p.m. after it was determined the woman was not contagious.

Hodas said passengers told him the woman had developed an unknown rash.

The woman, whose name was not released, was taken to a hospital. Her condition was not immediately known.