EPA interim final report on WTC background study, April 2003

NYC 9/11 Public Portal Document

The background 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 COPCs include asbestos in air’ by phase contrast microscopy equivalent (PCMe), phase contrast microscopy (PCM) and transmission electron microscopy (TEM) Asbestos Hazard Emergency Response Act (AHERA)\ asbestos in settled dust, lead in air and settled dust, dioxins in settled dust, polycyclic aromatic hydrocarbons (PAHs) in settled dust, fibrous glass and minerals including alpha-quartz, cristobalite and tridymite, hereinafter referred to as crystalline silica, and other mineral dusts including calcite, gypsum, and portlandite in both air and settled dust. These contaminants are discussed in detail in the peer review draft report "World Trade Center Indoor Air Assessment: Selecting Contaminants of Potential Concern and Setting Health-Based Benchmarks" provided as Attachment A.

2.3 Project Description Sampling was conducted in fourteen residential Manhattan buildings not impacted by the airborne dust plume that 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 shared laundry facility in each building. In total, EPA sampled twenty-five residential units and nine common areas within the fourteen buildings. Results of the Study are discussed in general terms and are not specific to the units sampled. In accordance with the agreement for Consent for Access for Enviromnental Sampling for the WTC Background Study, the addresses of the buildings and apartments, including the identity of the volunteers, will remain confidential.

’ The asbestos air samples were collected according to NIOSH 7400 (PCM). The sample filters were analyzed using a modified AHERA method. Although the total TEM (AHERA) fiber count was recorded, a separate PCMe count was recorded by modifying the AHERA method to coimt only fibers greater than 5pm (micrometer). It is this modified AHERA PCMe fiber count that was the basis of the asbestos test results and health based benchmarks.

2 The EPA regulates asbestos contaminated materials (ACMs) in schools via the Asbestos Hazard Emergency Response Act (AHERA) of 1986. The AHERA schools rule requires all public school districts and private schools to inspect all school buildings for ACMs; to develop plans to manage asbestos in schools; and to carry out the plans in a timely fashion. The rule also provides an opportunity for parents, teachers, and other school employees to become familiar with and involved in their school’s asbestos management programs.

WORLD TRADE CENTER BACKGROUND STUDY 7

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