Panel agenda for Air Quality After 9/11 conference, March 2004

NYC 9/11 Public Portal Document

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What was the nature of air quality at ground zero following the attack? According to

Professor Emeritus Thomas Cahill, head of the University of California and Davis’ DELTA

Group (for Detection and Evaluation of Long-Range Transport of Aerosols), a collaborative

association of scientists at several universities and national laboratories, conditions as the Site

were “brutal” for recovery workers. In 2002, DELTA researchers issued a report based on their

analysis of more than 8,000 air samples collected between October 2 and October 30, 2001, on a

rooftop at 201 Varick Street, one mile north of the World Trade Center. Additional samples were

collected through May 2002. In a press release dated September 10,2003, Cahill said:

“The debris pile acted like a chemical factory. It cooked together the components of the buildings and their contents, including enormous numbers of computers, and gave off gases of toxic metals, acid and organics for at least six weeks....”

The release goes on to say:

“In that hot pile, some of the debris’ constituent elements combined with organic matter and abundant chlorine from papers and plastics, and then escaped to the surface as metal-rich gases. These then either burned or chemically decomposed into very fine particles capable of penetrating deeply into human lungs. “In the trade-center air samples, Cahill identified four classes of particles that have been named by the EPA as likely to harm human health: □ Fine and very fine transition metals, which interfere with lung chemistry. □ Acids, in this case sulfuric acid, which attack cilia and lung cells directly. □ Very fine, un-dissolvable (insoluble) particles, in this case glass, which travel through the lungs to the bloodstream and heart. □ High-temperature organic matter, many components of which are known to be carcinogens.” ‘For each of these four classes of pollutant, we recorded the highest levels we have seen in over 7,000 measurements we have made of very fine air pollution throughout the world, including Kuwait and China,’ Cahill said.” “They [the 8,000 air samples taken at Varick Street] detailed very high levels of fine airborne particles—^particles that pre-September 11 EPA summaries had showed could raise a persons risk of lung damage and

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