NEW YORK (AP) -- Researchers are hoping interviews with survivors from the World Trade Center's north tower can help explain why dozens of people below the building's 93rd floor did not escape.
City and federal health officials think the personal accounts will shed light on what happened Sept. 11, 2001, immediately after hijacked American Airlines Flight 11 slammed into the building.
The officials say estimates show as many as 80 people died below the 93rd floor before the building collapsed. Thousands of others escaped safely, while people above the 93rd floor were trapped by the jetliner.
The study is one of three beginning this spring aimed at improving evacuation plans for high-rise buildings. Columbia University and National Institute of Standards and Technology are conducting the other two.
Officials with the city health department and the Centers for Disease Control and Prevention went to former trade center tenants last month for help in contacting survivors; interviewers hope to begin collecting the personal accounts next month.
``It is going to be a challenge, but we think that it'll provide critical perspective into what happened, what distinguishes those individuals that didn't make it out,'' said George Luber, a CDC epidemiologist. ``Is there something that those individuals had in common that we can identify in other similar workplaces?''
Luber said the study addresses the north tower, which was hit first, because the evacuation of the south tower was confusing _ some workers left when the north tower was struck, but others stayed in their offices.
Researchers have some preliminary hypotheses about the people who died below the 93rd floor, said Susan Wilt, assistant commissioner of the city's health department.
``Could it be a medical condition, or a disability or those in supervisory positions?'' she asked.
They hope to answer those questions by finding two survivors to comment on each of the dead, to get an accurate portrayal of the victims and their last moments. The study will then compare the experiences of those who died with those from a control group of survivors, gathered separately.
The studies by Columbia University and the National Institute of Standards and Technology are also using survivor accounts.
Columbia is examining the organizational aspects of the evacuation, such as emergency plans and fire drills. The institute expects its two-year investigation into the collapse of the towers to result in tougher building codes to improve skyscraper safety.
