NYC-WTC_000203528

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan * December 3,2002 Air Sampling for Hydrocarbons, Metals, Mercury & Silica Page 3 P. S. 234fManhattan)ATCPro]ectNoM5J1125-0279

METAL SAMPLE RESULTS

Metal samples were analyzed for aluminum, cadmium, chromium, cobalt, copper, iron, magnesium, manganese, molybdenum, nickel and zinc. The limits of detection ranged from less than 0.0001 milligrams per sample (mg/sample) for cobalt to 0.002 mg/sample for iron. The airborne concentrations were calculated by dividing the amount found in the sample by the volume of air collected.

Chromium and nickel were detected in all samples however both metals were also detected in both blanks. When the average chromium and nickel levels in the blank are subtracted from the amounts in the samples, the airborne concentrations drop below the limits of detection except in one sample collected from the West Playground where a nickel concentration of 0.007 mg/m^ was found. Any chromium and nickel detected were already in the filter and did not come from the ambient air except that one sample for nickel collected from the West Playground. A trace amount of iron was found in the West Playground sample but it also found in one of the blanks. When the blank concentration is subtracted from the amount in the sample, the airborne concentration drops below the limit of detection. Aluminum was detected in one indoor sample, however it was found in one of the blank samples at an even higher concentration. The actual sample concentration therefore was below the limit of detection.

The Enviroiunental Protection Agency (EPA) has set a screening level for hexavalent chromium (the more toxic form) in air of 0.6 micrograms per cubic meter of air (ug/m^), this assumes a continuous exposure for one year. These samples were analyzed for total chromium (trivalent and hexavalent). All Cr concentrations were below the EPA screening level.

The EPA screening level for nickel is 2 ug/m', the concentration detected in the West Playground sample "was below this level.

The EPA has no standard or screening level for Al, Mg or Fe in ambient air.

MERCURY SAMPLE RESULTS

Mercury (Hg) was detected m these samples at levels that were indistinguishable from that detected in the blanli.

The established regulatory value for mercury (OSHA: O.lmg/m^) is intended for industrial workplace exposures and is not generally applicable to office/school settings. There are no standards for mercury in indoor air in non-industrial situations. The EPA has no standard or guideline for mercury vapor in ambient air.

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