VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

Exposure and Human Health Evaluation ofAirborne Pollution from the World Trade Center Disaster Section I. Overall Purpose and Scope of Assessment The purpose of this document is to provide a preliminary assessment of the potential human health impacts associated with exposures to emissions caused by the September 11,2001, collapse of the World Trade Center (WTC) towers. This assessment focuses on a disaster that has already occurred, and it became a challenge to evaluate the seriousness of health impacts that may have resulted (or may still result) from past exposures to contaminants. This situation presents problems that are different from those faced in analyses to support the proactive establishment of environmental standards, to determine emission limits from air sources, and in similar regulatory venues where risk assessment procedures are used. In such circumstances, risk managers can make an active choice regarding the level of protection that is to be achieved and how uncertainties will be weighed in that process. In addressing exposures resulting from the WTC attack, those options are not available. Accordingly, this report attempts to take a practical, integrative approach to evaluating and conveying the potential impacts and their seriousness from a public health perspective.

Six contaminants/contaminant classes were evaluated in this assessment. These included: particulate matter (PM), metals (lead, chromium, and nickel), polychlorinated biphenyls (PCBs), dioxins, volatile organic compounds (VOCs; benzene and several others), and asbestos. Although hundreds of different substances have been measured in various media, these substances were selected for evaluation because monitoring indicates that they correlate with the disaster site in both time and space, and because they pose a potential concern for health impacts. PM was generated by the collapse of the WTC buildings, the recovery and demolition operations, and the lingering fire. Lead and asbestos were believed to be components of the WTC building materials. PCBs were likely used as dielectric fluid in transformers and capacitors. Dioxin and VOCs are produced as a result of combustion and volatilization from fuels. A screening of all substances was not possible in the time available. Instead, a judgement was made that the above listed chemicals might pose the greatest health concerns. Other contaminants may be evaluated in later reports.

Potentially exposed populations could include anyone who lives or works in the vicinity of WTC, such as cleanup workers, office workers, merchants, or residents. Available data were not always sufficient to evaluate the potential impacts to all populations from all contaminants. For example, it was decided that monitoring data for VOCs at Ground Zero could not be used to evaluate VOC exposure to Ground Zero workers. The reasons for this are twofold. First, most of the EPA data for VOCs at Ground Zero came from simple grab samples taken within plumes and within rubble piles. The principal purpose for this sampling strategy was to understand the source emissions of VOCs from the WTC rubble and fires, and to alert the Fire Department of New York (FDNY) and the contractors/union health/safety officers working at Ground Zero about conditions that posed immediate health concern to the workers. As such, these data were deemed not appropriate for evaluating human exposure and potential health impacts. Second, analyses of exposure of Ground Zero workers to VOCs were conducted by the Occupational

DRAFT-DO NOT QUOTE OR CITE 12 October 2002

NYC-WTC_000149093