EPA interim final report on WTC background study, April 2003

NYC 9/11 Public Portal Document

1.0 INTRODUCTION A Background Study of the Contaminants of Potential Concern (COPCs) in upper Manhattan was conducted in parallel to several other efforts to address the concerns of lower Manhattan residents regarding the potential risks from exposure to residual WTC dust and debris. These efforts were funded by FEMA through agreements with EPA and the City of New York (NYC).

While there are background reference levels for a few indoor air pollutants, comprehensive reference levels (i.e., normative concentrations) for typical residences do not exist for several reasons. In contrast to the situation for many outdoor air pollutants which have been routinely monitored for decades because of legislative mandates, no such legislation exists for indoor air pollutants.

Indoor monitoring has been generally limited because of its cost, the difficulty of obtaining access to residences due to privacy issues as well as the noise and inconvenience of sampling equipment and monitoring instrumentation. The size of a nationally representative monitoring network for residences could also be large and therefore require costly and complex studies because of the need to capture variability due to regional differences in housing construction, differences in residential types (e.g., apartments vs. single-family detached houses), seasonal differences in operation of the residence (e.g., heating vs. air conditioning), differences in human activities (e.g., smoking, cleaning methods...) occupant demographics and density, age of housing and related housing maintenance practices (e.g., use of lead-based paint). In summary, useful reference levels for air pollutants or contaminants indoors typically do not exist.

2.0 BACKGROUND AND PROJECT DESCRIPTION 2.1 Background In June 2002, EPA entered into an agreement with FEMA in order to continue to assess the impacts of possible contamination from WTC related dust in indoor residential environments. As part of this assessment, EPA needed to identify what levels of pollutants existed in indoor residential environments in New York City prior to September 11,2001. To accomplish this, EPA developed and implemented a plan for sampling and analyzing the dust present in residential buildings located in upper Manhattan that were not affected by the collapse of the WTC from which to infer contamination levels in downtown residential building prior to September 11,2001.

2.2 Purpose/Objective The objective of the Background Study was to determine indoor baseline levels or background concentrations for the presence of specific contaminants related to materials used during the construction of buildings, materials that are typically found within occupied buildings and any combustion byproducts caused by fires.

WORLD TRADE CENTER BACKGROUND STUDY 6

NYC-WTC_000145881