Establishing the WTC Dust Signature: Managing Post 9/11 Environmental and Damage Assessments

The collapse of the World Trade Center Towers following the catastrophic events of 9/11 produced a dust cloud that covered much of lower Manhattan. Thousands of private and public buildings were contaminated by the dust. Building owners in the vicinity of the collapse, worried about environmental impact to their damaged buildings, retained RJ Lee Group to assess the situation. A major objective of the study was to establish a set of baseline conditions to determine which components of the WTC dust were sufficiently above typical background dust levels in New York City so a quantitative signature could be developed. This signature would then be used to differentiate the structural and environmental impact of the WTC event on these buildings and to determine the appropriate remediation method.

We began by designing an overall comprehensive environmental program to manage the evolving studies. The plan included both a site-specific Health & Safety Plan (HASP) as well as site monitoring programs to protect both worker and community health. Next, we concentrated on assessing the damage impact of potential fall-out contaminants such as fuel oil, diesel fuel, particulates, asbestos, heavy metals, PCBs, PNAs and dioxins. The enormity of the task and the volume of samples anticipated required strict attention to recording details. To ensure these studies were executed properly, we developed customized software applications for the Personal Data Assistants (PDAs) we used to record our findings during sample collection, visual assessments, and other field activities. Using PDAs and customizable software, we increased the efficiency of field operations, minimized data entry errors, and streamlined the processing of more than 100,000 samples collected over a three-year period. Based upon these studies, we developed what is commonly known as the “WTC Dust Signature.” This signature demonstrated the unique characteristics of the finely pulverized dust and chemicals resulting from the WTC event and was used to indicate areas of impact in affected buildings.

RJ Lee Group also served as the lead scientific management team, supervising subcontractors including architects, engineers, toxicologists, analytical laboratories, and other scientific experts. We also established routine ongoing communication with the U.S. EPA and New York City & State officials to ensure acceptance of procedures, protocols, and transmittal of our findings. The resulting reports became the basis for the EPA’s ongoing remediation programs for buildings impacted by the WTC event.

To this day, RJ Lee Group’s studies represent the most comprehensive environmental impact studies ever performed in Class-A building structures and serve as a basis for catastrophic event response efforts where environmental damage is being evaluated. The resulting WTC Signature document was used as evidence in civil litigation and entered the public record via the judicial process.

To learn more about the RJ Lee Group’s involvement in WTC aftermath, please visit our memorial site: