NYC-WTC_000223537

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan January 7, 2002 Air Sampling for Dioxins Page 2 P.S. 234 /Manhattan) ATCPrpiectNpM5-1912S:0279

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 (EPA) has a screening level for dioxins m air of-0ri6 nanograms per cubic meter (0.16 ng/m^). A nanogram is a thousandth of a microgram (1 X 10’® gram). The EPA screening level is based on continuous exposure for one year. The Occupational Safety and Health- Administration (OSHA) has not established a Permissible Exposure Limit (PEL) for dioxins in air.

RESULTS

Each sample was analyzed for seventeen (17) 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). This provides a single value for the analytical results for each sample.

The results for both days are summarized in the table. A picogram is one one-thousandth of a nanogram (1 O’ ‘ gram).

A][RBGRNEDIOMNI^yELS(2AJL8TCDpEQ^ -DIOXIN LEVEL Lw 'V , " LOCATION^

Room 118 0.0018

2"“ Floor Hallway 0.0024

Cafeteria 0.0035

Room 315 0.0013

Outdoors 0.0014 Front Entrance Outdoors 0.0022 Roof Outdoors , 0.0019 Back Playground Outdoors 0.0017 North Courtyard Lab'Blank 0.000081

CITY_21MC100_002891167

NYC-WTC_000223538