VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

IV.f. Volatile Organic Compounds (VOCs)

VOCs are carbon compounds that exist exclusively in the gaseous phase in the ambient environment and include benzene, toluene, chloromethane, ethylbenzene, acetone, and styrene. VOCs have been associated with a variety of health effects, including immunologic, hematotoxic and neurologic effects; chromosomal damage; and cancer. VOCs are produced as a result of combustion of products containing carbon, such as plastics, wood, paper, carpeting, gasoline, and jet fuel. Thus, they would have been produced as a result of the WTC disaster.

Analysis of all VOCs released at the World Trade Center would require evaluating hundreds of different compounds. The list was narrowed down by emergency response personnel, representatives from EPA headquarters, EPA Region 2, NYSDEC, and NYSDOH. In this assessment, data for 14 VOCs were examined and screened, including acetone, benzene, 1,3 butadiene, chloromethane, 1,4 dioxane, ethanol, ethylbenzene, fi-eon-22, methyl styrene, propylene, styrene, tetrahydrofuran, toluene, and xylenes. These VOCs were chosen on the basis of frequency of detection, concentration, toxicity, and carcinogenicity. Two of these 14 VOCs, freon-22 and methyl styrene, were not systematically measured outside of Ground Zero. Freon- 22 was measured only at the WTC Chiller Plant and methyl styrene was only measured at Ground Zero. For this reason, freon-22 and methyl styrene are not evaluated in this report. Additionally, because no screening standards are available for propylene, a health assessment cannot be conducted for this chemical. Therefore, a total of eleven VOCs were evaluated for this report.

To evaluate the VOC exposures, a variety of screening benchmarks were used, including OSHA PELS and STELS, ATSDR acute and intermediate inhalation MRLs, and EPA Superfund Technical Support Center (STSC) provisional subchronic RfCs. If none of these benchmarks were available, the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) for an 8-hour exposure and the NIOSH RELS were used. The goal of this assessment was to evaluate effects due to short-term exposure, thus screening tools that are based upon lifetime exposures to a chemical (i.e. EPA RfC values or ATSDR chronic MRLs) were not used.

IV.f.l. Evaluation of VOCs at Ground Zero The majority of the EPA data collected for VOCs were within Groimd Zero (North Tower Center, South Tower Center, and Austin Tobin Plaza) and nearby locations. For example, for acetone, benzene, ethylbenzene, and 1,3 butadiene, more than 500 samples were taken in the restricted zone near and within Ground Zero, where authorized personnel were directed to wear respirators. The majority of the measurements taken were grab samples that were usually collected within a 4-minute period. Samples at North Tower Center and South Tower Center were taken in potential hot spot areas such as plumes, areas of fire and combustion, and steam releases. The efforts at these two locations were subjective and were intended to capture potential worst case emissions. Samples at Austin Tobin Plaza were taken at a breathing zone height, but were still grab samples and were not purposively where workers were currently working, but where they might work or where there was visible smoke to contend with. Thus, collected samples at the three sites caimot be considered representative of the general air quality to which workers were exposed. Rather, the principal purpose of the EPA sampling at Ground

DRAFT-DO NOT QUOTE OR CITE 102 October 2002

NYC-WTC_000149046