Air Today . . . Gone Tomorrow Article|
A 'Chemical Factory' in
By Laurie Garrett, Newsday Staff
Writer, September 11, 2003
The air that hovered over New York in the months after by the collapse of the
Twin Towers contained an unprecedented combination of chemicals, scientists said
yesterday. As such, they said it may be impossible to forecast the long-term health
Scientists from government and university laboratories gathered yesterday for the first
time to compare findings about the dust, debris and polluted air in the aftermath of 9/11,
in a conference at the annual meeting of the American Chemical Society.
The picture that emerged from the presentations depicted an unprecedented chemical event
that evolved minute-by-minute, throwing a stew of compounds into the air. Researchers said
one molecule detected had never been found in air before. The plume was marked by a mix so
complex, the content varied centimeter by centimeter, researchers said.
Ground Zero fires smoldered for months and reached temperatures of 1,800 degrees, creating
what a scientist characterized as a "chemical factory" that brewed new
compounds. One effect was a sort of mini-ozone hole, in which chlorinated compounds
scavenged hydrogen and other atoms off molecules, transforming them into volatile gases.
"The fact that the plume did not stay in one direction means the exposures to people
were intermittent," said Paul Lioy of the Environmental and Occupational Health
Sciences Institute of the University of Medicine and Dentistry in New Jersey. "Here
it was, a catastrophic event. Initial exposures were basically a blackout - exposures
people will, cumulatively, never see in a lifetime again. The problem we have now is we
don't know the long-term, lifetime, health consequences. We just don't know."
There was a degree of disagreement among experts in attendance. Thomas Cahill, an air
pollution expert from the University of California, said starting on Oct. 3, 2001, air
monitored on the roof of a building in the West Village, a mile north of Ground Zero,
showed "unprecedented ambient levels" of fine particulate matter, sulfur, acidic
aerosols, heavy metals and other dangerous compounds. "I have sampled more than 7,000
samples of very fine aerosols for Kuwait [during the 1992 oil fires], China and so
on," Cahill said, "and October 3 was the worst." But NYU environmental
science expert George Thurston said most of the pollutants measured were normal for New
York. Thurston's group started collecting air samples on Sept. 28 from NYU's Downtown
Hospital, five blocks northeast of Ground Zero, and comparative samples from northern New
Jersey and eastern Greenwich Village. He said by October, fires and dust contributed only
a third of New York's pollution, and by January it had no real impact. Most scientists did
not agree. The EPA's Joseph Pinto used optical density analysis of videos and photos shot
on 9/11 to determine the wavelengths of light scattering to determine what chemicals and
debris were present. "What I'm coming up with really should be viewed as lower
limits," Pinto said. "You can see clear enhancement, one hundred to a
thousand-fold, in pollution levels due to the World Trade Center."
Lioy's group is creating three-dimensional models of the plume and debris movement. The
intense heat of Ground Zero blew the plume upwards, creating a "loft effect," he
said, which actually protected New Yorkers from the worst of the chemical onslaught,
though it also lifted the gases and particles over Manhattan and dropped them on Brooklyn
and Sandy Hook, N.J. U.S. Census Bureau data are being added to the computer model,
creating a neighborhood-by-neighborhood picture of human exposure that the researchers
hope will help health officials determine locales at risk for long-term health problems.
One molecule, described by the EPA's Erik Swartz, was present at levels "that dwarfed
all others": 1,3-diphenylpropane. "We've never observed it in any sampling we've
ever done," Swartz said. He said it was most likely produced by the plastic of tens
of thousands of burning computers.
Roger Clark of the U.S. Geological Survey's Colorado laboratory led a team that provided
the first strong pollution data for the White House, delivered on Sept. 17. The next day
the White House announced operations would shift from rescue to recovery, because the heat
level precluded the possibility of survivors beneath the rubble.
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