NYC-WTC_000151957

NYC 9/11 Public Portal Document

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Trade Center Air Held Unprecedented Amounts of Very Fine Particles, Silicon, Sulfates, Metals, Say UC Davis Scientists http://www.news.ucdavis.ed u/default.lasso?-database=news_db.fmp_&-layout=new s_detail&-response=search/news_detail.lasso&-logicalOp'^r&-recordlD8684&-s earch February 11,2002

In the most thorough analysis yet of the dust and smoke blown through lower Manhattan after the collapse of the World Trade Center, researchers at the University of California, Davis, today described unprecedented clouds of very fine particles that should be considered in evaluating rescue workers’ and residents’ health problems. Based on their findings, the UC Davis researchers also recommended specific cleaning methods for contaminated apartments, offices, schools and other indoor spaces. “No one has ever reported a situation like the one we see in the World Trade Center samples,” said UC Davis researcher Thomas Cahill, Ph.D., an international authority on the constituents and transport of airborne particles. “The air from Ground Zero was laden with extremely high amounts of very small particles, probably associated with high temperatures in the underground debris pile. Normally, in New York City and in most of the world, situations like this just don’t exist." Cahill, a UC Davis professor emeritus of physics and atmospheric sciences and a research professor in applied science, heads the UC Davis DELTA Group (for Detection and Evaluation of Long-range Transport of Aerosols), a collaborative association of aerosol scientists at several universities and national laboratories. The DELTA Group has made detailed studies of aerosols from the 1991 Gulf War oil fires, volcanic eruptions, global dust storms, and most recently Asia. The Manhattan air samples were collected at the request of a U.S. Department of Energy scientist from Oct. 2 through mid-December, by a DELTA Group air monitor placed on a rooftop at 201 Varick St., one mile north-northeast of the trade center complex. The samples were collected continuously in eight separate size modes from coarse (12 micrometers diameter) to ultra-fine (0.09 micrometers diameter). Regional meteorology showed that the site at Varick Street could have received material from the World Trade Center site about half the time. The samples were periodically shipped back to Davis, where the DELTA Group analyzed the samples for size, shape and composition. They used a suite of seven techniques including synchrotron-induced X-ray fluorescence (at DOE’s Advanced Light Source at Lawrence Berkeley Laboratory), scanning transmission ion microscopy and proton elastic scattering analysis (at DOE’s Lawrence Livermore National Laboratory), and soft beta mass measurements and scanning electron microscopy (at UC Davis). “The UC Davis DELTA Group’s ability to measure and analyze particle size, composition and time continuously, day and night, is unequaled,” Cahill said.

NYC-WTC_000151958