NYC-WTC_000195194

NYC 9/11 Public Portal Document

1. Introduction

In an effort to provide information to the public on cleaning methods that would be effective in removing dust and contaminants generated by the WTC collapse and recovery efforts, EPA, in concert with FEMA and NYC, began a study of a building that had been impacted. The building was located on Liberty Street, just south of the WTC site. On June 14, 2002, EPA and its contractors commenced the WTC Residential Confirmation Cleaning Study to confirm the adequacy of various cleaning and vacuuming methods that may have been used by the residents of lower Manhattan and professional cleaning companies to clean dust and debris from residential living areas.

1.1 Background/Objectives

Shortly after the collapse of the WTC, NYCDOHMH, EPA and others provided the residents of lower Manhattan with recommendations on cleaning methods through the media, fact sheets and community meetings. These recommendations were based on previously established cleaning procedures that were proven to be effective in removing layered particulate matter and debris, with minimal dust generation. The WTC Residential Confirmation Cleaning Study was conducted to provide the residents with additional information. The effectiveness of the cleaning methods tested in the study was evaluated through the collection and analysis of pre-cleanup and post­ cleanup samples, and comparison of the resulting analytical data to health-based screening levels for the COPC. Table 1.0 presents the primary clearance criteria used to determine cleaning effectiveness.

The study’s COPC included; asbestos in air by phase contrast microscopy equivalent (PCMe) lead in air and settled dust, dioxin in air and settled dust, PAH in air and settled dust, fibrous glass and man made vitreous fibers (MMVF) in air, and alpha-quartz in air. More detail on the selection of these compounds is included in Section 1.2.

In addition to evaluating data for the COPC in their respective media identified above, data was also evaluated for COPC that were analyzed using alternate analytical methods [e.g., asbestos in air using PCM and transmission electron microscopy (TEM) Asbestos Hazard Emergency Response Act (AHERA), COPC in other media (e.g., asbestos, MMVF, and alpha-quartz in settled dust), compounds that were included as part of the crystalline silica analytical analysis (e.g., cristobalite, tridymite, calcite, and gypsum in air and wipe samples]. The results from these additional analyses were primarily used to evaluate the cleaning methods as there were no health­ based benchmarks for comparison. The exception would be the asbestos in air PCM and TEM AHERA results, which in addition to being used to evaluate the cleaning methods, were also compared to their respective regulatory criteria.’ These regulatory criteria are referred to as

^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 PCM-equivalent (PCMe) count was recorded by modifying the AHERA method to count only fibers greater than 5 pm (micrometer). It is this modified-AHERA PCMe fiber count that was the basis of the asbestos test results and clearance criterion.

’The regulatory clearance criterion for TEM AHERA was 70 S/cm\ converted to 0.022 S/cc, based on a volume of 1200 cc. The regulatory criterion for PCM AHERA was 0.01 fee based on a volume of 1200 cc. 4

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