Nearly 20 years ago, then-American Airlines pilot Dan Elwell was scheduled to attend a ceremony at the Pentagon when he saw the World Trade Center on fire. When Elwell called the Pentagon about the event, he heard an explosion over the phone and later realized it was Flight 77, one that he routinely bid on to fly with his Washington-based flight crew, that hit the Pentagon. "I knew everybody on the crew. That's sort of tough to think about that -- how close you came to being on that trip," Elwell said. The events of 9/11 changed the aviation industry, including the trajectory of Elwell's career. He later joined the Federal Aviation Administration to work on aviation and safety policy.

Almost 20 years after the attacks on Sept. 11, 2001, New York City's Chief Medical Examiner's Office has identified two more victims through DNA analysis. So far, only 60% of the people who died at the World Trade Center that day have been officially identified.

A study of more than 5,700 firefighters who responded to the Sept. 11, 2001, attacks at the World Trade Center in New York City found weight loss may reduce their risk for lung disease, researchers reported in the American Journal of Respiratory and Critical Care Medicine. "The lessons from our investigation can be applied not only to firefighters but to the millions of city dwellers exposed to air pollution on a daily basis," said senior author Dr. Anna Nolan.

A study of more than 5,700 firefighters who responded to the Sept. 11, 2001, attacks at the World Trade Center in New York City found weight loss may reduce their risk for lung disease, researchers reported in the American Journal of Respiratory and Critical Care Medicine. "The lessons from our investigation can be applied not only to firefighters but to the millions of city dwellers exposed to air pollution on a daily basis," said senior author Dr. Anna Nolan.