NYC-WTC_000182787

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan December 14, 2001 Wipe Sampling for Dioxin Page 2 Stuvvesant High School (Manhattan) ATC Project No. 15-19125-0246

SUBSTANCE DESCRIPTION

“Dioxins” or “dioxin” is a name used for a group of chlorinated multi-ringed organic compounds that includes polychlorinated dibenzo dioxins (PCDDs) and polychlorinated dibenzo furans (PCDFs). They are related to polychlorinated biphenyls (PCBs). PCDDs and PCDFs are not produced commercially except for research purposes. They occur as trace level by-products of combustion and industrial chemical processes. Combustion of PCB-containing oils, such as during an electrical transformer fire, is known to produce dioxins. Burning of some plastics may also produce dioxins. Dioxins are toxic and are considered to be carcinogenic.

The Environmental Protection Agency has a screening level for dioxins in air of 0.16 nanograms per cubic meter (0.16 ng/m^), A nanogram is a thousandth of a microgram (1 X 10'9 gram). The Occupational Safety and Health Administration (OSHA) has not established a Permissible Exposure Limit (PEL) for dioxin in air or on surfaces.

The New York State Department of Environmental Conservation (NYSDEC) has set 0.0006 parts per million (ppm) as the allowable concentration of dioxin in soil.

WIPE SAMPLING RESULTS

ATC submitted three wipe samples for PCDDs/PCDFs (plus one blank) to Pace for analysis. A copy of the laboratory report is provided in Attachment 1. Samples were taken from areas specified by the parents association consultant. The sample area for each sample was 100 square centimeters (lOOcm^), The areas sampled were:

• 1 si floor main entrance wall; • 2nd floor bridge entrance wall; • Mixed air plenum-AC#2 or AC #1

Each sample was analyzed for sixteen (16) PCDD/PCDF isomers. The results for each isomer were then converted to 2, 3, 7, 8 tetrachloro-dibenzo-p-dioxin (2, 3, 7, 8-TCDD) equivalents by multiplying by an established equivalency factor (See Attachment 2), This provides a single value (in nanograms) for the analytical results for each sample.

The results of the samples are shown in the following table.

CITY_21MC100_003101460

NYC-WTC_000182788