NYC-WTC_000196831

NYC 9/11 Public Portal Document

Mr. Bernard P. Orlan » January 8,2003 Air Sampling for Hydrocarbons, Metals, Mercury & Silica Page 3 P. S. 89(Manhattan)ATC ProiectNo. 15-19125-0297

This is not an unusual situation especially during custodial cleaning of the school which had been conducted around the time these samples were collected during the winter break.

The likely sources were cleaning materials or disinfectants containing some alcohols.

No other hydrocarbons were found above the limits of detection in any of the samples collected.

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 was detected in all samples however it was also detected in both blanks. When the average chromium level in the blanks is subtracted from the amounts in the samples, the airborne concentrations drop below the limits of detection. Any chromium detected were already in the filter and did not come from the ambient air. Zinc was detected in both blanks but not in any air samples, indicating that zinc may be a random contaminant of the filter medium.

The Environmental 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 detected in the samples higher than the average of the two blanks were below the EPA screening level.

The EPA has no standard or screening level for zinc in ambient air.

MERCURY SAMPLE RESULTS

Mercury was detected in these samples at levels that were indistinguishable from that detected in the blank.

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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