The dust was deceptively normal—what it mostly looked like was the inside of a vacuum cleaner bag, fluffy and gray, the color of dirty New York snow. At first the dust had an odd pinkish tint, a blush that was as curious as it was repulsive because it suggested blood and human remains. It was probably caused by some chemical reaction, and it did not last long. Eventually, the dust took on the more neutral color of dry bone. When Lioy and his colleagues put the dust under a scanning electron microscope or subjected it to polarized light microscopy, it began to reveal some of its secrets. They could see the awesome destructive force of the collapse. It was as though the buildings and everything they contained had been put through a gigantic wood chipper, and then those remnants passed through a coffee grinder, were thrown into a gigantic mortar, and were smashed with a pestle until all that was left were indistinguishable particles, a powder of the past. Lioy theorizes that the initial plume that was released as the towers came crashing to the ground was made up of larger, lighter, material that traveled farther. People caught in the plume described it as being swallowed by night.
Much of the dust was composed of cement particles, the minute remnants of the towers’ 110 floors—each the size of a football field and 4 inches thick. In seconds, the hardened concrete had been ground into bits smaller than any controlled demolition ever created. Because of the way the floors had crashed on top of each other in rapid succession, the concrete had literally been pulverized. When the scientists subjected it to chemical analysis, they found that the dust had a surprisingly high pH value because of the cement dust, which made it very alkaline and caustic, significantly increasing its ability to harm the delicate nasal passages and throats of workers on the pile. Cement is ubiquitous in cities, but its standard form is solid. After the twin towers came apart, an extraordinary transformation took place. The rock-solid concrete in the towers was turned into windborne specks. The air above and around ground zero was literally filled with cement. Lioy found that the pH was highest in the coarse particles, which the body generally can filter out before they travel too deeply into the respiratory system. The smaller particles, which can easily slip in and, therefore, are more dangerous, were not so caustic because acid particles in the smoke, with their low pH values, acted to neutralize them. Two researchers at New York University, George Thurston and Lung Chi Chen, came to a similar conclusion about different pH values for coarse and fine particles after analyzing dust samples that had been collected around ground zero. They predicted that health effects caused by the dust would be severe in the short run because the dust was so caustic, but that the body’s natural defenses would trap most of the material before it could reach deeply into the lungs, minimizing long-term impacts. Their thesis would be severely tested in the coming months.
To determine how irritating the dust was, Stephen H. Gavett, a scientist at the EPA’s National Health and Environmental Effects Research Laboratory in North Carolina, exposed mice to it.3 Gavett isolated the fine particles of less than 2.5 micrometers in the dust and blew them into the lungs of the mice at high concentrations, equivalent to what might have been in the air right after the towers came down. The dust caused mild to moderate lung inflammation, but importantly, it left the mice hypersensitive to things that could trigger asthmalike restrictions in the lungs. For most people with the same level of sensitivity, cold air and cigarette smoke can trigger an asthmatic attack. Lioy worked with scientists at the National Toxicology Program on a test to replicate the effects of the dust, exposing lab animals to both fine and large particles. They came up with similar results that persisted in the lab animals somewhat longer than they had in the EPA study. But the scientific journal they sent the results to found fault with the study, and it was never published. The experience showed Lioy that national health authorities might not be as interested in the fallout from 9/11 as he was. Even so, it was becoming increasingly clear to him that ground zero dust did not conform to the typical pattern with which aerosols move into and out of human lungs. The dust was full of surprises.
Lioy first presented some of his findings to residents of Lower Manhattan on October 18, 2001, at a meeting on NYU’s Washington Square campus that was organized by the scientific community. But the data on the caustic nature of the dust was largely overlooked because the hundreds of residents of Lower Manhattan who attended the meeting were fixated on other elements that seemed scarier—namely, lead and asbestos. Mixed in with the caustic particles of cement were the asbestos fibers that Lioy had feared he would find.
Asbestos is an incredible mineral, made up of long, thin strands that can withstand heat and pressure. Man has used asbestos for thousands of years, and it became widely industrialized in the latter half of the nineteenth century. Asbestos becomes most dangerous when the fibers break loose and can be breathed in. They can become lodged in lower airways, where they cause irritation that can lead to debilitating diseases like asbestosis, as well as fatal ailments like lung cancer and a rare disease of the thin lining of the lungs called mesothelioma. The asbestos fibers are normally long, tough, and thin—so thin that 100 of them laid side by side are no wider than a single strand of human hair. Once they get inside the lungs, they are almost impossible to get out. Although considered nearly indestructible, the asbestos fibers in the trade center dust had broken into smaller pieces because of the force of the collapse. Some had attached to fibrous mats of other elements and compounds, making them even more insidious.
The actual amount of asbestos in two of Lioy’s dust samples was relatively small—.8 percent chrysotile asbestos—but still significant. The dust he had scooped up on Market Street contained 3 percent asbestos. Even small amounts can cause lasting damage after many years, but asbestos could not account for the cough workers had started experiencing almost immediately.
Lioy, who had investigated toxic exposures for over 30 years, had never seen anything like the trade center dust. Neither had anyone else. It contained an unprecedented variety of materials, a tragic mixture whose toxicity was yet unknown. In time, he and his colleagues identified more than 150 different elements and compounds in the dust. They found common construction debris that included particles of plaster, glass, synthetic foam, vermiculite, and charred wood. They identified dead skin cells, the type typically found in household or office dust. They also found plenty of exotic elements, including titanium, from the white paint used in the towers’ offices. Most worrisome were the benzene, lead, and dioxin that were released when miles of PVC pipe in the twin towers went up in flames. Lioy classified the ground zero disaster as a “dual nature event,” the first phase being the collapse of both towers and the second the fires that raged at over 1,000° for days and then smoldered at lower temperatures for months, leading to incomplete combustion that released dangerous soot. Using transmission electron microscopy, the scientists found polycyclic aromatic hydrocarbons and were able to isolate individual fibers of asbestos. When they tested for inorganics, they found gold, lead, and the mercury from thousands of fluorescent light bulbs.
The list would have contained much more than the 150 elements and compounds if the scientists had continued to classify the material that appeared in ever smaller quantities. Had they carried on this work, they would eventually have had to list human DNA from the vaporized victims, although in infinitesimally small amounts (1 in one sextillion, or 10 to the minus 20) because even 3,000 human souls made up only a miniscule percentage of the overall mass of the trade center. The New York City fireman who had shouted “We’re breathing dead people” was correct, in a scientific sense. But Lioy knew that even if he had continued to categorize the dust into smaller and smaller amounts that could separate out human DNA, he would not have come up with enough to link the genetic material to any of the victims, at least not with currently available methods and equipment.
Though the Institute’s scientists could not carry their investigation that far, they did find strands of what they easily identified as human hair. Whereas the su
per-hard concrete of the buildings’ floors had been ground to dust, the hairs had survived intact. Lioy was not prepared to subject these remains to DNA analysis, either. He believed the hair probably came from the carpets of the office towers, the accumulated human detritus of 40 years of daily commerce. The hair and cells caught in the carpets could have come from the thousands of victims. Or they could have come from anyone—including him—who had ever worked in the buildings or visited long enough to drop a single strand of hair. Perhaps in decades to come science would be able to reliably match DNA from such samples. But not now.
Even without the genetic stamping, the material in Lioy’s lab jars clearly constituted the sum of countless individual lives and the passage of those lives inside the walls of the doomed buildings. The minute particles of gold Lioy found might have started as a wedding band or an earring given as a birthday gift. The tiny strands of black polyester may have come from the back cover of a picture frame that once held the photo of a beloved parent or a childhood friend. And some of the ubiquitous cellulose in the dust may have originated in the desks where men and women whiled away countless hours in their high-rise offices. Or it may have come from the memos those people wrote while they were daydreaming of the beach, or from the pages of the calendars on which they noted the ordinary milestones of daily living—the dentist appointments, birthdays, and special anniversaries that could not be missed.
Lioy spent as much time studying the dust as anyone in the scientific community. His growing intimacy with the material eventually led him to see it not just in scientific terms, but in a humanistic way as well. Those two sides of his personality had been wrestling since September 11, and occasionally the personal side burned through without him being aware. At a 2005 conference, Lioy summed up the tragedy before an audience of students and faculty at Montclair State University in New Jersey. He narrated a short list of the chemicals, minerals, and compounds that had been detected in the dust, making clear that the entire list was extremely long and all-inclusive. Finally, he abandoned the language of the laboratory all together. “The trade center dust contains everything we hold dear.” The words were uncharacteristically emotive for a traditional scientist like Lioy, who hadn’t even realized what he’d said until it was brought to his attention. It astonished him to think that he had dropped his professional detachment so fully. But it’s clear that those sentiments must have come from a deep emotional well that usually is off-limits in his scientific work.
This time emotion prevailed, at least temporarily.
On the same day that Lioy and Weisel collected their dust samples with shovels and plastic bags, the U.S. Geological Survey (USGS) sent one of its most sophisticated imaging spectrometers over ground zero.4 Mounted on a Canadian-built de Havilland Twin Otter airplane, the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) is capable of detecting heat and identifying chemical bonds in molecules based on how they absorb infrared light. The spectrum of colors in the resulting images can reveal the presence of different minerals, including asbestos. As the AVIRIS flew over ground zero, it picked up more than three dozen hot spots. Some measured 800°F; a couple were a blistering 1,300°F. (Most were gone or greatly reduced by September 23, when the AVIRIS again flew over the area.) The imaging also picked up trace amounts of what was believed to be asbestos. On Monday, September 17, a two-person USGS ground crew began gathering dust samples. They collected material from 35 different spots within half a mile of ground zero and managed to get much closer to the debris pile than Lioy had on his first expedition. They took two samples from the coating on steel beams that had just been removed from the pile. Two other samples came from indoor spaces that presumably had not been diluted by rain. It took the crew two days to grab everything. All the samples were sent to USGS laboratories in Denver, where they went through a battery of tests. The results were in line with what Lioy’s team was finding. Trace amounts of asbestos showed up in most of the outdoor samples. But the material taken from the steel beams confirmed that asbestos that had been used as insulation on at least some portions of the buildings was still there on 9/11. These samples were laden with asbestos fibers—as much as 20 percent chrysotile asbestos, a known carcinogen.
The Denver lab also found that the calcium sulfate in the concrete made the dust highly alkaline. As with Lioy’s samples, the USGS discovered pH values as high as 10, which made it as strong as ammonia. The pH of indoor samples that had not been diluted by the September 14 rain were even higher, hovering around 12. At that level, the dust was about as caustic as drain cleaner. This crucial information was posted September 27 on a USGS website that was accessible only to the EPA and other government agencies. Even though Lioy and the NYU researchers had independently come to the same conclusion about the corrosive nature of the dust, many clinicians and ground zero workers didn’t find out about it until an out-of-town newspaper reported the results, along with startling headlines, five months later.5
At the Institute, Lioy and his colleagues continued their multifaceted investigation. One group studied the dust plumes and created a computer simulation of their movements.6 Using motion graphics like those on TV weather reports, the physicists showed that the ominous clouds rose on updrafts caused by warm temperatures and then were buffeted by September winds. Over several days, the winds pushed the plume around so that it snaked across the metropolitan region, slashing over Brooklyn, twisting back again over Manhattan north of Canal Street, and then sweeping across the Hudson to New Jersey before blanketing the harbor again. The animation indicated that a broad swathe of the metropolitan area, not just Manhattan’s financial district, had been touched by the airborne dust, which eventually settled in those areas as well, although less densely because of the distance from ground zero.
As the energy that carried the plume up and out eventually dissipated, the dust drifted back down to Earth, coming to rest on hundreds of buildings, seeping underneath thousands of windows, sucked into countless air-conditioning ducts, and infiltrating every surface. Much of it would quickly be washed away, mopped up, or swept into the trash. But the tiniest of particles would remain for years and would rise like unwelcome ghosts every time something disturbed them.
Since 2001, Paul Lioy has given away over half of the dust he collected to scientists from all over the world who have asked to study the material. He finally stopped sharing it when he feared that the composition of the dust had changed so much with time that testing would no longer produce reliable results.
Still, requests come in, and Lioy sometimes makes the long walk from his office down the hallway of the Institute, around a corner, and into the cold room.
“Like a police evidence room,” he says, pulling open the heavy metal door. The refrigerated chamber, about 12 feet by 12 feet, is lined with five open metal shelves that go from floor to ceiling, front to back. On a shelf on the left side of the room is a pair of ordinary plastic storage bins, clear with blue lids. They are marked “Dr. Lioy’s WTC samples—Please do not touch.” No one does.
Lioy hauls one bin back to his office. As time has passed, he’s moved on to other issues and eventually immersed himself in a huge national children’s study with Dr. Philip J. Landrigan of the Mount Sinai Medical Center. But he can never get far from the dust. He has written more than a dozen scientific papers about his investigations into the exposure risks at ground zero, and he is often asked to weigh in on issues involving health and environmental issues related to the disaster. In 2009, the National Society of the Daughters of the American Revolution gave him a patriotism award for his work on 9/11 dust. On a bookcase in his office he keeps the hard hat, respirator, and gloves he wore at ground zero. And on the wall is a photograph he took while he was there. The debris pile looms over several workers who are pitching in with the rescue and recovery operation. One of them wears a respirator mask. One has a mask hanging around his neck. A third doesn’t wear any respiratory protection at all. It is a preview of an unfolding disaster.
Lioy was determined to be guided by science, not emotion. He had felt himself slip over from cold analysis to the warm emotions of anger, fear, and awe, and he did not want to be there again. His instruments and graphs would tell the story. He feared that the frenzy over asbestos was overshadowing the dust’s more immediate threats. Moreover, no one knew what was in the gasses and smoke that belched from the pile in the first few days of utter chaos. And that worried him, because he believed that all the responders who were exposed to that material immediately after the collapses probably breathed in a dangerous combination of toxins that could interact in ways that might not be clear for decades. People who had been exposed were frightened and wanted answers, and they wanted them right away.
Through it all, Lioy harbored a painful over-riding doubt. He knew better than most that certainty about the real danger of the dust may not come for a long time. Some workers who were exposed to asbestos mixed with the gases from the burning rubble might not become ill until 30 years after they left ground zero. But many are already sick, far sicker than the results of tests of lab animals would have suggested. Something else clearly was going on, but what? Certainty won’t come for decades, but if the dust—combined with the gases and smoke—truly was toxic, waiting that long could cost lives. If the threat that the dust could cause cancer and other fatal diseases could not be discounted outright, waiting could cause tremendous pain and endless anguish. Uncertainty and fear could make victims of those who escaped becoming victims on 9/11.
City of Dust Page 3