Indoor environmental quality survey fax, Nov 21, 2001

NYC 9/11 Public Portal Document

ambient group inc. NATIONAL HEADQUARTERS

Indoor environmental quality surveys 55 WEST 39Th STS' I2rn FLOOR Water treatment consulting NEW YORK, NEW YORK 10018 Asbestos & lead field services TEL: (212) 944-4615 Regulatory compliance programs FAX: (212) 944.-4618 Air, water & soil analytical laboratories WER: WWW.AMBIBNTGROUP.COM

November 21, 2001

Mr. Elliott Zuckerman Director of Property Management Cushman & Wakefield a/a/f New York Mercantile Exchange One North End Avenue New York, New York 10282

Re: Environmental Monitoring for Combustion Byproducts

Dear Mr. Zuckerman:

In order to address additional environmental concerns raised by the prolonged combustion process that continues at the World Trade Center site, in early October we instituted additional analysis of environmental compounds that might be generated by the combustion process in the outdoor air. The equipment used and the analysis performed were chosen in accordance with EPA Compendium of methodsfor the Determination of Toxic Organic Compounds in Ambient Air. Samples were analyzed for chlorinated dioxins, PCBs,'brominated dioxins and polycyclic hydrocarbons (PAHs). The four groups represent over 300 types and/or isomers of chemicals that are known to be hazardous substances associated with combustion.

Ambient air analysis, as opposed to occupational analysis, has many unique differences that make sampling, analysis and interpretation difficult. For instance, ambient sampling requires a very large sample volume for analysis, which in turn requires specialized equipment and a lengthy sampling period. In addition, each group of diverse compounds must be prepared separately and analyzed by distinct procedures. Finally, there are no reference standards with which to compare the results of airborne concentrations in order to determine the health risk to office workers.

One approach that is often used is to transform the air concentrations of all the different specific congeners of PCBs, dioxins and furans into Toxicity Equivalents (TEQs) of 2,3,7,8 tetrachloro-p-dioxins (2,3,7,8 TCDD). 2,3,7,8 TCDD is thought to be the most hazardous of this group of compounds and is given a weighting of 1, while other less toxic compounds are given a weighting of less than 1 relative to 2,3,7,8 TCDD.

With that said, our findings indicate that the levels found at One North End Avenue between October 16 and October 29, 2001 are as follows: Sampling Period 2001 TEQs 10/16-10/23 10/23-10/29 13 Day Average PCBS 0.004 pg/m3 0.001pg/m3 0.002pg/m3 Chlorinated Dioxins and Furans 0.27 pg/m3 0.40 pg/m3 0.33.pg/m3 Total TEQ of all chlorinated 0.27 pg/m3 0.403 pg/rn3 0.33 pg/m3 cogenitors 1 picogram (pg) = 0.000000000001 gram GLEN COVE, NY MIAMI, FL CHICAGO, IL ORANGE, CA 516 609-0009 305 86o-oiol 312 527-5526 714 282-2525 L:\2001\Investigations\L.etters\Dioxin Summary For Mercantile exchange 11,20,01.doc

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