9:59 a.m. September 11, 2001 and 10:28 a.m. September 11, 2001: Much Dust Released from Collapses of WTC Twin Towers

The World Trade Center twin towers collapse—the south tower at 9:59 a.m. and the north tower half an hour later at 10:28 a.m. [CNN, 9/12/2001; New York Times, 9/12/2001; New York Times, 9/12/2001; Washington Post, 9/12/2001; MSNBC, 9/22/2001; Associated Press, 8/21/2002] The collapses create huge dust clouds that roll through the streets of Lower Manhattan, breaking windows and forcing dust and debris into the interior of surrounding buildings.
Composition of dust - Chemicals and materials present in the billowing clouds include pulverized plaster, paint, foam, glass fibers and fragments, fiberglass, cement, vermiculite (used as a fire retardant instead of asbestos), chrysotile asbestos, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, polychlorinated dibenzodioxins, polychlorinated dibenzofurans, pesticides, phthalate esters, brominated diphenyl ethers, cotton fibers and lint, tarry and charred wood, soot, rubber, paper and plastic. [Allergy, Asthma & Immunology Online, 9/15/2001; CNN, 11/4/2001; Lioy et al., 7/2002; US Geological Survey, 10/2002 ] The dust has an extremely high pH. [US Geological Survey, 11/27/2001; St. Louis Post-Dispatch, 2/10/2002]
Distribution of dust and debris - The debris will be distributed very unevenly throughout the city because of their varying weights. Dusts containing relatively heavy components, such as pulverized concrete and glass, will settle near the World Trade Center, whereas dust containing lighter components, like asbestos, will fall to the ground in greater relative concentrations at a further distance. Heavy metals—including zinc, strontium, lead and aluminum—will also be deposited a relatively large distance away from the disaster site. [Lioy et al., 7/2002; US Geological Survey, 10/2002 ; Jenkins, 7/4/2003 ]
Composition of smoke/debris plume - Combustible materials buried in the rubble of the towers provides fuel for a fire that will burn until December. Many of the materials are made of substances that when burned release highly toxic fumes. According to Thomas Cahill, a professor of physics and engineering, “The debris pile acted like a chemical factory. It cooked together the components and the buildings and their contents, including enormous numbers of computers, and gave off gases of toxic metals, acids, and organics for at least six weeks.” [BBC, 9/10/2003; Reuters, 9/11/2003]
The two towers contained as many as 50,000 personal computers, each containing small amounts of mercury and about 4 lbs of lead. The towers also contained roughly 300 mainframe computers. [Nordgren, Goldstein, and Izeman, 2/2002 ; Kupferman, 2003 ]
Thousands of fluorescent lamps in the buildings contained mercury. [Nordgren, Goldstein, and Izeman, 2/2002 ; Kupferman, 2003 ]
Thousands of chairs and other office furniture contained chemicals like polybrominated diphenyl ethers, which pose dangers similar to PCBs. [Nordgren, Goldstein, and Izeman, 2/2002 ]
Several of the WTC’s tenants are known to have had toxic materials on site. For example, there was a Secret Service shooting range that kept millions of rounds of lead ammunition on hand. And a US Customs lab had in its inventory thousands of pounds of arsenic, lead, mercury, chromium, and other toxic substances. [Kupferman, 2003 ]
Other products in the buildings included synthetic fabrics, plastics, laminates, the di-electric fluids that encase electrical cables, capacitors, electrical cable insulation and transformers. The toxins resulting from the combustion of these materials include toxic lead, volatile organic compounds, dioxins (see December 27, 2002), mercury, nickel, vandium, sulphur, PAHs, PCBs and furans. [Nordgren, Goldstein, and Izeman, 2/2002 ]
Distribution of smoke/debris plume - The aerosol plume will move from the WTC site in Lower Manhattan directly over Brooklyn where it will drop much of its toxic debris, contaminating the neighborhoods of Brooklyn Heights, DUMBO (Down Under the Manhattan Bridge Overpass), Cobble Hill, Boerum Hill, Park Slope and beyond. New York City Council member David Yassky, who is in Brooklyn campaigning on this day, will later recount in an interview with Newsday, “There was a film of dust on everything—on cars, stores, everywhere in Brooklyn Heights. If you were there, as I was, you saw several hours of debris rain down on your neighborhood.” [Newsday, 8/23/2002; Newsday, 9/30/2002]