This article is part of Discover's package on the health effects of 9/11 air pollution on the people in New York City.

Click here to read about the city and federal governments' failure to protect ordinary citizens.

At an age when many of his peers are practicing their golf swings, 65-year-old Philip Landrigan is smack dab in the middle of a crucially important health project: He is the lead doctor researching the sometimes deadly health effects of living and working in lower Manhattan in the aftermath of the 9/11 terrorist attacks on the World Trade Center.

What's more, he's just getting started on an even bigger undertaking: the National Children's Study, a landmark field investigation that will follow 100,000 American children from conception to age 21.

Landrigan's office is at the Mount Sinai School of Medicine in New York, where he heads the Department of Community and Preventive Medicine.

Q: Your department is monitoring the health effects from the collapse of the World Trade Center. When the towers collapsed, two million tons of dust containing cement, asbestos, glass, lead,and carcinogens rained down on lower Manhattan. Yet less than a week later, the EPA said it was safe to go there and breathe the air. Now we know that erroneous assessment may have put thousands of people at risk for serious chronic health problems, and even death.

A: [EPADirector] Christine Todd Whitman's statement that the air in Manhattan was safe to breathe was stupid and ill-considered because she was making a very strong assertion with almost no data. I wondered how she could say this—it's like a doctor telling a patient that the patient is healthy before he's done any tests.

At that point, only minimal air sampling had been done because all the air monitors had been destroyed. And most of the early sampling was focused on asbestos because we thought that asbestos was the big hazard. It took a few weeks before we realized that it was the complex mix of chemicals and dust that was the hazard—asbestos was just part of the puzzle—especially the pulverized concrete, which was extremely alkaline.

Like breathing Drano. Unfortunately, that's true. And the concentrations of dust in the air were so high that they overwhelmed all the normal defenses of the human respiratory tract, and people inhaled ounces of dust into their trachea or their bronchi.

Did you have any inkling about what was going to happen? Not immediately because it took time for that recognition to evolve. It was about one to two months later that we began to see a few people with a persistent cough in our occupational medicine center here at Mt. Sinai, which is the biggest in the region. And another symptom that didn't get as much attention was extraordinary inflammation of their upper airways, and nasal sinuses, which was very painful. These observations started accumulating through the fall and winter, and by the spring of 2002, we realized we had a lot of people with respiratory problems.

We got some money from the National Institute of Environmental Health Science, and did a quick survey of members of the Iron Workers Union, the guys that operate the heavy cranes and who got down there within hours of the attacks. We compared 110 ironworkers who had been down at Ground Zero versus a couple hundred who were elsewhere in New York City. And there was a very striking difference in the rate of respiratory symptoms.

That was when we went to the National Institute for Occupational Safety and Health, and said there is a need for a structured medical monitoring program for the people who worked down there. They set up two big programs here in New York City. One was at the Fire Department, which focuses on the active duty firefighters and that program has seen about 15,000 people. The other is based here at Mt. Sinai, which anchors a consortium of five institutions around the city: Bellevue, Stony Brook Medical Center on Long Island, the University of Medicine and Dentistry of New Jersey, and Queens College. We're the hub of this consortium, which has now seen about 20,000 people, and we're continuing to follow up.

But it's hard to capture everyone who worked at the site. Many of them live outside of Manhattan, and some are immigrants who don't speak much English. Efforts have been made because we all recognize the problem. The fire department has the best records of all because they are a paramilitary organization—they knew exactly who was where when and they can command people to come in for physical examination. We've got all the other workers, and we've done a pretty good job, but not as good as the firefighters. One of the problems is that nobody kept a very good record of who was working on the site, and there are estimates that go from 40,000 to 100,000 people were down there.

The truth will never be known because there's no way to completely recapture them. My own guess is that between the two groups, we've probably seen two-thirds to three-quarters of everyone who was down there. But even now, six years after the events, we're still getting 500 new people every month who are finally coming in for medical assistance; they have just now gotten sufficiently worried or pushed by their spouse or their partner.

Now some experts are saying there's a third wave of Ground Zero illnesses—cancers and in particular, myelomas. That's still in the very early stages. We have seen some cases of cancer in people who were down at Ground Zero, and we're trying right now to verify precisely which kind of cancers those are because that obviously makes a difference. What we don't know is whether these cases are related to Ground Zero, and if this is the beginning of a trend or just background noise. Frankly, only time will tell. Mesothelioma as a result of asbestos, for example, typically takes two or three decades to makes its appearance.

So the ultimate death toll from the World Trade Center could be in the tens of thousands. Who knows? But it's almost certainly going to be greater than what we know today.

There are 46,000 children who attend school in lower Manhattan. Six months after the attacks, you testified before Congress that the indoor environment at the schools was safe. Do you think this all-clear signal might have been premature? Have any follow-up studies been done on these kids? In retrospect, there was more indoor contamination than we initially realized. In some cases, windows were blown out and the contamination was painfully obvious. But it took a while to realize that there were a number of other buildings that didn't react swiftly enough to close their air intakes, so the contaminated dust got taken up with the air handling systems.

The City of New York, with support from CDC, has set-up a registry for people of all ages who live or work in lower Manhattan. They've collected detailed medical information on 71,000 people, whom they are continuing to follow.

That's our best hope of seeing what's happened to the children.

So we could possibly see illnesses 20 or 30 years hence? We could and it could be many decades from now. Children have many more years in future life than we adults, and if they are exposed to asbestos, for example, they've got seven or eight decades to manifest any disease.

The government initially was reluctant to recognize that people were damaged from exposure to this caustic dust. What do you think finally turned the tide?

The truth. It just became painfully obvious within a couple of months that people were damaged, and the press was filled with stories about the World Trade Center cough. The critical event was the David Prezant paper in the New England Journal of Medicine [September, 2002] on the World Trade Center cough. David Prezant heads the medical follow-up program at the fire department. It became very difficult after that for people to say no harm was done.

The Bush Administration is trying to cut off access to this kind of critical information. Yes. The EPA has shut some of their libraries and they've pulled stuff off their website. An interesting way in which this plays out relative to the World Trade Center is that there have been senior officials within the Department of Health and Human Services who've seriously proposed shutting down the Centers of Excellence at Mt. Sinai, at Bellevue, at the fire department, and the other institutions that are providing a high level of care to the 9/11 victims. They're proposing to replace them with a voucher program where you'd give a chit to any worker who could document that he or she was down there and let them go to their private doctor in New Jersey, Ohio, or Florida—wherever they happened to live. They've said to pursue such a policy would "preserve freedom of medical choice." We fought this vigorously because it would have several adverse effects.

First, it would have a negative effect on the individual workers, who have complicated lung diseases caused by unique exposures and who are often simultaneously suffering from mental health problems. These complex issues require the kind of care you only get in a big teaching hospital, where people have expertise in dealing with this. You send them out to a well-intentioned but inexperienced general practitioner in the suburbs and it's almost inevitable that the person isn't going to get such good care.

The second consequence of this action—and I think that this may be part of the motive—is that if you disperse this population and sent them out to a widely scattered network of private practitioners, then the centralized collection of data would come to an abrupt end. And we would no longer have statistics on what had happened after 9/11.

Do you think federal officials are trying to escape culpability for exposing people needlessly to the caustic dust? I don't think there's any real way to answer that question because that speaks to motive, and I can't get inside their heads. But I can look at the external actions and say what they're proposing to do is medically ill-advised and makes absolutely no sense.

Whenever a patient asks me where they should go because they've been diagnosed with a certain disease, my immediate answer is to go to the doctor who's already seen 5,000 people with your disease. You don't want to put yourself in the hands of someone who's doing it for the first or the second time, and yet that's precisely what this proposal advocates, which is very short-sighted and ideologically driven.

And protects the government and corporations from billion-dollar lawsuits. Maybe, but I'll just describe it as ideology.

It's difficult because we've had to spend an enormous amount of effort fighting what I consider an unnecessary fight to preserve the programs that are doing the right thing. Quite frankly, the production of scientific papers from the World Trade Center project has been slowed by virtue of the fact that many colleagues and I have had to make multiple trips to Washington—giving congressional testimony, having private meetings with staff—to advocate what we all think is the right thing. But the trouble is if we didn't do it, then we'd have no scientific papers to write.

So the Bush Administration has done everything they can to slow the process down. Yes.

Do you get angry? Yes, but I've never seen much virtue in sitting around sulking. You've got to get past that, and turn it into action. What we've done in the case of the scientific papers from the World Trade Center, for example, is that we've accelerated that process. I've taken my best epidemiologist, David Savitz, who has agreed to chair a high-powered working group that meets every couple of weeks. They plan to get eight or nine papers out within the next six months so that we get the findings from the World Trade Center experience out in front of the public.