NYC-WTC_000199886

NYC 9/11 Public Portal Document

Metals (December 5, 8, and 12, 2001)

Several metals were not detected in 8 samples collected inside and outside of the school. For the metals detected, indoor concentrations were generally lower than outdoor levels. Metals concentrations were generally higher in the samples collected on December 5 and decreased in the December 8 and December 11 samples. In the December 5 samples, common metals such as iron and aluminum were detected both inside and outside the school. In addition, copper and chromium were also detected both inside and outside of the schools, with chromium detected at up to 0.442 ug/m’ outside and 0.348 ug/m^ inside, and copper at up to 0.692 ug/m^ outside and 0.41 ug/m^ inside. These levels are within the range of urban background levels published by the U.S Department of Health and Human Services. For the samples collected on December 5, chromium was also detected in the blank sample at a level (0.383 ug) similar to those detected in the air samples (0.309 ug to 0.54 ug), indicating that the actual chromium concentrations in air may be significantly lower than indicated by the analyses. ATC, the firm that performed the sampling for the Board of Education, estimated that actual chromium concentrations in the samples would decrease by 80 to 90 percent when the blank concentrations were removed. On December 8 and 11, only copper and chromium were detected in any of the air samples inside or outside of the school. Chromium concentrations on December ranged up to 0.262 ug/m^ outside the school and 0.270 inside the school. On December 12, chromium was only detected in one of the four indoor samples and two of four outdoor samples at maximum concentrations slightly lower than on December 8. The USEPA is utilizing a screening level for hexavalent chromium of 0.6 ug/m^. These samples were analyzed for total chromium, which includes both the hexavalent and trivalent species. The total chromium concentrations in all the samples were below this USEPA screening level.

Cyanide( December 6,8, and 11,2001)

Cyanide was not detected in either of two samples collected on December 6,2001 at levels above the method blank. On December 8, cyanide was detected in both samples outside of the school as well as in the method blank sample, at concentrations (corrected for blank levels) of 0.0042 and 0.0052 mg/m\ and on December 11, cyanide was detected in both outside samples at blank corrected concentrations of 0.0008 mg/m^ and 0.0048 mg/m^. All the measured cyanide concentrations are below the USEPA Region 9 PRO for cyanide in air, adjusted for a school exposure scenario, of 0.0087 mg/m^. Sources of cyanide in the environment include vehicle exhaust, industrial sources, and natural biogenic processes.

Hydrocarbons

On December 5, 2001, trace levels of one target compound, acetone, were detected in one outdoor sample (0.347 ppm) and two indoor samples (0.101 ppm and 0.116 ppm). In addition, undifferentiated hydrocarbons were also detected in two indoor samples. Painting and cleaning operations were being conducted on that day and these results are

6

CITY_21MC100_008972442

NYC-WTC_000199891