VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

11 and that first measurement. For some chemical classes, like VOCs, an exposure and health evaluation for this time period cannot be conducted because the data do not exist. This could be critical for benzene, for example, which could have been present at very high levels near September 11 due to volatilization from gasoline and aviation fuel. EPA-ORD researchers are working to use modeling and available data and meteorological information to reconstruct . probable exposures for some contaminants such as PM. Some preliminary results of plume dispersion are included in this report. When this and other work on immediate post-September 11 issues has been completed, further health evaluations of this critical window may need to be conducted.

Similarly, data regarding contaminant levels prior to September 11, or levels that might be considered background and typical for New York City (NYC), do not exist for all compounds because such measurements have not been performed routinely in all urban areas. Where information specific to NYC is available, such data are discussed. Otherwise, general urban of general background concentrations are identified and used to place the post September 11 monitoring results in perspective.

This assessment evaluates the potential for health impacts fi-om the exposures that have occurred from September through about April of2002. Most monitoring was discontinued in July of 2002, but data only through April was available at the time this evaluation was conducted. The air concentration data shows that, by April 2002, initially high levels decreased to background levels, with most reaching background by December 2001. However, the data collected between April and July, 2002, will be examined in the coming year to see if there were any elevations which could change the findings presented in this report.

As more data become available, further assessments may be conducted in order to evaluate more chemicals, more pathways, the indoor environment, the period between April and July, 2002, and other identified data gaps. Local and Regional needs, peer review and public comments on this assessment, and professional judgment will be used to determine the direction of future assessments.

DRAFT-DO NOT QUOTE OR CITE 14 October 2002

NYC-WTC_000149095