EPA interim final report on WTC background study, April 2003

NYC 9/11 Public Portal Document

Residential Confinnation Cleaning Study)

These efforts have been conducted simultaneously to ensure that residents are provided the opportunity to have any WTC residual material removed from then- units as quickly as possible.

This report presents the results of the WTC Background Study conducted by EPA. Results from this Study caimot account for the variability with indoor environments in general (i.e., cross contamination from outdoors to indoors, way of life and level of cleanliness). The measurements are limited to each specific apartment or common area sampled at that specific time the samples were collected.

Project Objectives / Overview

The objective of this Background Study was to determine and/or estimate indoor baseline levels or background concentrations for the presence of specific contaminants related to building materials and combustion byproducts that may be released when building materials are burned during a fire. The backgroimd concentrations derived from this Study will be used to supplement the health­ based benchmarks established in the "World Trade Center Indoor Air Assessment: Selecting Contaminants of Potential Concern and Setting Health-Based Benchmarks" document and were identified as a potential source of alternate cleanup values if the health-based benchmarks were not able to be achieved. The selected Contaminants of Potential Concern (COPC) includes asbestos, lead, dioxins, polycyclic aromatic hydrocarbons (PAHs), fibrous glass and minerals including crystalline silica (i.e., a-quartz, cristobalite, tridymite), calcite, gypsum, and portlandite.

The number of buildings, residences and common spaces samples were determined by what could practically be achieved to avoid impeding the project. The geographical area for the Background Study (78th Street and North) was selected based on preliminaiy modeling of meteorological data on September 11, 2001 and shortly thereafter. The modeling was performed by EPA’s Office of Research and Development. The distance of buildings sampled in the Study with respect to the WTC site ranges from 8 to 19 kilometers (5 to 12 miles).

Sampling was conducted in fourteen residential buildings not impacted by the airborne dust plume which emanated from the WTC site. When possible, samples were collected from two residential units and from one common area, such as the lobby, hallway, stairwell, or building laundry facility, in each building. In total EPA sampled twenty-five residential units and nine common areas within the fourteen buildings. Results of the Background Study are discussed in general terms and are not specific to the units sampled.

WORLD TRADE CENTER BACKGROUND STUDY 2

NYC-WTC_000145877