EPA interim final report on WTC background study, April 2003

NYC 9/11 Public Portal Document

WTC ambient air, indoor air, and indoor/outdoor bulk dust monitoring data were reviewed. Data sources included EPA's ambient air and bulk dust/debris monitoring program www.epa.gov/wtc. OSHA's air and dust monitoring data and the NYCDOHMH/ATSDR indoor air pilot program (NYCDOHMH 2002). A concerted effort also was made by the COPC committee to identify and review additional sources of WTC related data from other governmental agencies (e.g., U.S. Geological Survey, NYC Board of Education), academic institutions, environmental organizations, and the private sector.

A semi-quantitative screening process was performed on the collected sampling data, referenced above. Based on frequency-of-detection, concentration and inherent toxicity, contaminants that exceeded health-based screening levels for the ambient air were identified. Dioxin and PAHs were added to the COPC list by this process. In addition, building constituents with carcinogenic (asbestos) or irritant effects (fibrous glass, crystalline silica) that were consistently found in bulk and indoor dust samples were identified as COPCs (NYCDOHMH 2002). Finally, lead was included based on a comparison of sampling data with existing regulatory standards. Collectively, the resulting group of contaminants (asbestos, lead, dioxin, PAHs, fibrous glass and crystalline silica) are called "contaminants of potential concern" or COPCs in this report.

4.0 SAMPLING METHODOLOGY Once building access was obtained and sampling scheduled, air and settled dust samples were collected from each of the fourteen buildings and shipped to the laboratories for analysis. All samples were collected and analyzed in accordance with the approved Quality Assurance Project Plan (QAPP) for the WTC Background Study, dated August 2002. The procedures used for sample collection, analysis, data validation, data management and evaluation are described in or provided as an attachment to the approved QAPP which will be furnished upon request.

4.1 Sampling Procedures Samples were collected from twenty five residential units and 9 common spaces (i.e., seven basement laundry rooms and two hallways). Sampling consisted of: indoor air samples of airborne fibers and particulate matter; microvacuum samples of settled dust on carpeting, area rugs, upholstered fabric furniture and/or drapery; wipe samples of settled dust from ceilings, walls, bare floors, counter tops or table tops; and bulk dust samples from window air conditioner filters. All samples were collected from areas routinely used and occupied by residents, such as, living rooms or bedrooms and in common areas, such as, entrance hallways or basement laundry rooms.

A summary of the sample collection and analytical procedures used are provided in Table 4-1 of this report. The following subsections provide brief descriptions of the sampling procedures to place the subsequent discussion of results in context. WORLD TRADE CENTER BACKGROUND STUDY 11

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