This segment was originally broadcast on Sep. 10, 2006. It was updated on Sep. 5, 2007.
On Sept. 11, 2001, thousands of workers rushed into lower Manhattan while everyone else was rushing out. They spent day and night on what became known as the "pile," searching for survivors and, later, remains in the worst of conditions. The cruel irony is that thousands of them are now getting sick. And as Katie Couric first reported last year, a growing number of studies confirm they're getting sick because of all the time they spent breathing the dust at ground zero.
In all there were about 40,000 people who worked on the pile - a collection of firefighters, policemen, construction and utility workers. One of them was 30-year-old New York City Police Det. James Zadroga. When the planes hit the World Trade Center, he drove straight to ground zero and stayed for weeks. His father, Joseph Zadroga, says he remembers that shortly after that his son started getting sick.
"Every morning he would wake up and he said he would be coughing and hacking, and this black stuff would come up out of his lungs," Det. Zadroga's father remembers. "And he just didn't know what was happening to him. He couldn't figure out what was happening to him."
His doctors didn't know either. Before long, James needed to inhale medication to breathe. And when doctors took a scan of his lung, instead of healthy pink tissue, his was black. Then one morning in 2006, James' father woke up to an unusual silence - his son wasn't coughing.
"I went upstairs and soon as I opened the door, I saw him on the floor. I didn't even have to go in there. I knew he was gone," Joseph Zadroga tells Couric. "And we spent the next two hours with him before we called anybody. And then we had them come to take him."
Asked what the autopsy of his son revealed, Zadroga says, "The doctor said, to the best of his knowledge, that Jimmy died from the results of working at the World Trade Center."
The coroner wrote on the autopsy report that the failure of James Zadroga's lungs was directly related to 9/11. It was the first time a death had been officially linked to inhaling the dust created when the towers fell. It was an unprecedented toxic brew - approximately one million tons of pulverized concrete, glass, asbestos, PCB's, lead and more than 400 chemicals. No one had ever dealt with anything like it.
"The air was so thick that everything was stuck in your mouth, in your nose. You were pulling large pieces out, coughing like crazy. You could not but inhale and swallow tons of material," recalls Dr. David Prezant, the Chief Medical Officer for New York City's Fire Department, who was caught in the dust cloud when the first tower fell.
Asked how quickly he noticed that people were showing the effects of breathing in this air, Dr. Prezant says: "What we noticed when we were down there, all right, is that everyone was coughing. Every firefighter, every EMT, was coughing. And then we went back down there the second day and the third day and everybody was still coughing. And by the end of the first week everybody was still coughing."
And it turns out that Prezant is also suffering in a minor way from the aftereffects.
"Well that's the good thing about being down there, from my perspective," he says. "I was able to realize I had this cough and I realized that this is a problem."
What was it about the dust at ground zero that made it so unbelievably toxic?
"The biggest problem was that it was pulverized building materials that wind up having a very high alkalinity - almost like lye, all right, or Drano - that when you inhale it or swallow it, it's burning your entire nose and airway and stomach," he explains.
But most workers thought they would be OK. In part, they say, because of what they heard early on from public officials, including then-New York City Mayor Rudy Giuliani.
"As you get beyond the epicenter of recovery site, the asbestos levels are either safe or nonexistent," the mayor said.
Christine Todd Whitman, the head of the Environmental Protection Agency, said this at the time: "Everything we've tested for, which includes asbestos, lead and VOC (Volatile Organic Compounds), have been below any level of concern for the general public. Obviously for those working down here, these are very important," she said, holding up a respirator mask.