VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

A total of 257 chloromethane monitoring results were evaluated at sites surrounding Ground Zero. A summary of the available screening benchmarks and exceedences is shown in Table 12. As with all VOCs, all grab sample exceedences were taken in a restricted zone, and in the time frame from late September to early October. It is noted that all of the samples that showed exceedences at Greenwich and Liberty were taken at ground level and that the October 1 measurement was taken at groimd level in a plume. Measurements taken at this site September 24 - 27 and on October 2 and 3 were all at levels below 0.02 ppm. From these data, it appears that exceedences did not last more than 4 days. At Liberty and Trinity, the exceedence detected was 0.82 ppm on September 26, and it was noted that this measurement was taken at ground level in a plume. Measurements taken on September 22, September 23, and on October 26 did not show exceedences.

Ethylbenzene: Ethylbenzene occurs naturally in petroleum and coal tar and can be released into the air from burning oil, gas, and coal The median level of ethylbenzene in city and suburban air is about 0.00062 ppm (ATSDR, 1999).

Breathing high levels of ethylbenzene (above 100 ppm) can cause dizziness, tightness in the chest, and eye and throat irritation. Short-term exposure of laboratory animals to high concentrations of ethylbenzene in air may cause liver and kidney damage, nervous system changes, and blood changes. No data exist to evaluate the short-term effects of low levels of ethylbenzene exposure in humans or animals. The EPA-STSC provisional subchronic RfC for ethylbenzene is adopted directly from the EPA RfC for a lifetime exposure. The EPA-STSC confidence level in this derivation is low. The EPA RfC is based on developmental effects seen in female rats that were exposed to ethylbenzene throughout their pregnancy. Adverse effects in this study were not seen at levels below 100 ppm (EPA, 1999a).

A total of 338 ethylbenzene monitoring results were evaluated at sites surrounding Ground Zero. A summary of the available screening benchmarks and exceedences is shown in Table 13. As with the other VOCs, exceedences occurred in the restricted zone in the latter part of September and early October. A value of 0.4 ppm ethylbenzene was detected at Liberty and Trinity and it was noted that this sample was taken in a ground-level plume. Three samples obtained between September 16 and September 23 and a breathing zone sample taken on October 26 were all below 0.05 ppm.

The 24-hour ethylbenzene samples that were detected were three orders of magnitude (1000 times) lower than these grab sample exceedences; 10 out of 13 samples were non-detected. This demonstrates again the difference between grab samples taken within a plume and the 24- hour average concentration of the VOC.

Toluene: Toluene occurs naturally in crude oil and is added to gasoline. Toluene is also used in making paints, paint thinners, fingernail polish, lacquers, and adhesives. It can also be detected in cigarette smoke. Urban concentrations of toluene have been estimated to be aroimd 0.003 ppm (ATSDR, 2000b). The background concentration reported by EPA Region 2 for toluene is approximately 0.002 ppm (annual average for a Brooklyn location over the period 1994- 1998).

DRAFT-DO NOT QUOTE OR CITE 108 October 2002

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