The former officer, Cesar Borja, 52, had been in intensive care, breathing through a tube, at Mount Sinai Medical Center, awaiting a lung transplant. Hospital spokeswoman Lauren Woods confirmed the death late Tuesday.
Borja's son, college student Cesar Borja Jr., was invited by Sen. Hillary Rodham Clinton, D-N.Y., to attend President Bush's speech as a reminder to the president of workers who were stricken with a host of illnesses after exposure to toxic World Trade Center debris.
The younger Borja learned of his father's death in a phone call while eating dinner around 6:30 p.m. but insisted on attending the president's 9 p.m. speech - in memory of his father.
The senator called Borja's death a "terrible tragedy."
The son, she said, "is a courageous and remarkable young man. His sense of duty to his father and to the mission that brought him to Washington is inspiring and heartbreaking."
The son's comments earlier in the day showed he was aware of just how critical his father's health situation had become — and why it was still important for him to speak out in Washington.
"It's a very emotional time, and it's very difficult," said the son. "My father is a symbol of those in need, in desperation."
The Hunter College student said he came to Washington to make the point that there are many more whose lives are threatened by their exposure at ground zero.
"9/11 is not over. It didn't end in 2001. It is still affecting my father and numerous other first responders," he said. "My father is an extreme example of what can happen and what may and will happen in the future."