NYC-WTC_000202104

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan February 25, 2002 Wipe Samples for Dioxins Page. 2 P. S. 89 ('Manhattanl ATC Project No. 15-19125-0297

ATC submitted three (3) wipe samples for PCDDs/PCDFs (plus one blank), to Pace for analysis. Copies of the draft laboratory analysis results are provided in Attachment 1. Samples were taken from areas specified by the parents association consultant. The sample area was one square meter (m^).

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. This provides a single value (in nanograms) :for the analytical results for each sample. The sample locations and the results are shown in the table:

DIOXIN WIPE SAMPLE RESULTS (2,3, 7,8 TCDD EQUIVALENTS) January 25, 2002

1st Floor Hallway-north/DXl , ist Floor nallway-south/DX2 2®^ Floor Hallway-south/DX3 0.0008'3 Field Blank/DX4 0.00

Tlie concentrations on indoor surfaces ranged from 0.000055 to 0.00083 nanograms per square meter (ng/m2). The dioxin concentrations in these sample are below the NYSDOH guideline.

It is not possible to determine when the 2, 3, 7, 8 - TCDD equivalents detected in these samples were deposited. Dioxin samples were not collected from these locations prior to December 20, 2001. •

It is our pleasure to provide these indoor environmental services to the NYC Board of Education. If you have any questions about this, report, please call (212) 353-8280, extension 212.

Sincerely, ATC ASSOCIATES n

James R. Cohn, CIH, CSp Regional Manager Industrial Hygiene Division

Attachment

CITY_21MC100_005390237

NYC-WTC_000202105