NYC 9/11 Public Portal Document
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6. Dioxins — There are no standards that establish safe levels of dioxins in bulk or wipe
samples.
After reviewing various data, Ambient chose a level of 1 ppb as a level requiring risk
management decisions. Based on this criterion, no elevated dioxin levels were detected. Also,
the most toxic of the dioxins, 2,3,7,8 — TCDD, was not detected in any of the samples. The
dioxins will be cleaned as part of the dust removal. See appendix G for raw data.
Based on the above, Ambient recommends that all floors be remediated using asbestos abatement
project techniques due to the contaminants that compose the dust. The dust contains metals,
fiberglass, cement, mercury, PAHs, and low amounts of asbestos. All porous surfaces, including
carpeting, ceiling tiles, fabric workstation partitions and chairs must be completely disposed.
Non-porous surfaces should be HEPA-vacuumed and wet wiped. The HEPA-vacuuming process
should capture all particulate matter such as asbestos, metals, PCBs, dioxin, PAHs along with
other dust components (i.e. Cement dust, decayed organic matter, fiberglass etc.).
NYC-WTC 000124630
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