Chain of custody form for DEP environmental samples, 2001

NYC 9/11 Public Portal Document

Background Following the attack on the World Trade Center, residential living spaces in the immediate vicinity of ground zero were impacted by dust and debris. Samples of dust and debris collected by EPA from the streets of lower Manhattan contained asbestos at levels greater than one percent of sample mass in approximately 35 percent of the 160 samples taken between September 11, 2001 and October 10, 2001. A study of residential unit interiors proximal to the WTC site was funded by FEMA, and implemented by ATSDR and NYCDOHMH with EPA support. This study concluded that although air sampling indicated that asbestos in air benchmarks had not been exceeded, residual material in the dust was attributable to the WTC attack and collapse. Preliminary results of this study were provided early in 2002. Final results were issued in September 2002.’

Shortly after the disaster, 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.

Objectives In an effort to provide additional information to the public on cleaning methods that may be effective in reducing contaminants from dust generated by the WTC collapse and recovery efforts, EPA, in concert with FEMA and NYC, commenced a study of a building on Liberty Street, just south of the WTC site, that had been heavily impacted by the coUapse of the twin towers. The purpose of the study was to confirm the adequacy of various cleaning and vacuuming methods used by residents and professional cleaning companies, in the aftermath of the attack, to clean dust and debris from residential living areas.

Project Implementation EPA and its contractors commenced the WTC Residential Confirmation Cleaning Study on June 14, 2002. The study addressed cleaning of a complex mixture of contaminants, including construction debris and fire-related compounds. EPA was unaware of a precedent for an indoor environmental cleanup with such a diverse set of parameters; however, time pressures did not allow for conducting extensive research on potential cleaning techniques in a controlled setting. The real-time need to determine the effectiveness of the cleaning methods being used by residents, and being employed in the WTC Dust Cleanup Program, drove the decision to field test the effectiveness of the standard dust removal methods in a heavily impacted, unoccupied building.

Eleven cleaning methods were selected for testing and assigned to residential units within the building according to the levels of observed dust. An attempt was made to test each method in units with both significant and minimal levels of dust.

Multiple endpoints were used in the study to ensure that the complexity of the dust was comprehensively considered. Analytical results were compared to health-based benchmarks for pre-selected COPC to determine if the cleaning was successful in achieving these values. The

’New York City Department of Health and Mental Hygiene/Agency for Toxic Substances and Disease Registry (NYCDOHMH). (2002). Final Report ofthe Public Health Investigation to Assess Potential Exposures to Airborne and Settled Dust in Residential Areas ofLower Manhattan. 2

NYC-WTC_000145700