Invisible Attacks: Defending Against a Chemical Threat

January 2012
Topics: Sensor Technology, Prevent Terrorism
As part of the planning for the new World Trade Center, developers are applying knowledge from a year-long MITRE study mapping chemical vapor detection systems.
Homeland security must be prepared to defend against invisible attacks.

As the new World Trade Center complex rises from the streets of Lower Manhattan, developers, architects, and builders recognize that it's more than an office complex.

The memorial and new buildings at the site of one of the worst attacks on U.S. soil are symbols of the country's resilience and continued leadership in the world. For that reason, it is important that planners anticipate that the World Trade Center complex and the thousands of people who pass through each day might again be terrorist targets.

"Next time, rather than a truck bomb as in 1993 or fuel-packed jumbo jets as in 2001, the weapon could be represented by any number of threats, including chemical," says Taylor Senf. Senf is an associate department head in the Homeland Security Systems Engineering and Development Institute (HSSEDI™), the federally funded research and development center MITRE operates for the Department of Homeland Security.

The developers of the World Trade Center are now using the results of a year-long MITRE study of chemical vapor detection systems to help prepare for—and respond to—such an attack.

The study didn't begin with the World Trade Center in mind. It began as a study for Angela Ervin, program manager for the DHS Science and Technology Directorate (DHS S&T), Chemical and Biological Defense Division (CBD). Ervin had commissioned the study to support a project at DHS S&T, the Advanced Chemical Vapor Detection System (ACVDS) Project.

MITRE's Chrissy Vu, a senior artificial intelligence engineer, led the study analyzing chemical vapor sensor technologies. As a second component of the study, MITRE researchers provided system architecture, planning, and development recommendations by developing framework scenarios for integrating chemical vapor detectors into existing building infrastructures. As part of that work, the team delivered a "best practices" document for chemical detection, based on open source research, lessons learned, and outreach to government and academic experts.

Assessing the Technology

The biggest challenge in the project was assessing the state-of-the-art chemical detection technologies. Specific information on chemical sensor characteristics is not readily available. "That information is hard to come by, especially in the chemical-sensing area, because so much of it is proprietary," Vu says. In addition, no formal standards exist for measuring chemical detector performance. Testing and evaluation parameters vary, making an "apples to apples" comparison of data very difficult.

In the end, the team created a matrix of 339 different sensors with more than 40 distinct sensor characteristics. The ACVDS technical team, including MITRE engineers Donald Bryan, Anna Gradishar, Samar Guharay, Charles Laljer, Sichu Li, and Lindsay Petersen, developed a system to rank the sensors by effectiveness, reliability, and breadth of screening capability.

To develop architecture and planning recommendations for those sensors, the team investigated how chemical agents behave—a factor that would determine where a builder would place the sensor. "Many chemicals behave differently. Some rise like smoke, while others remain suspended or sink. Some disperse quickly, while others linger in the environment. Different chemicals in different concentrations pose different threats to human health," Vu says.

The type of sensor that customers use will depend on the most likely chemical threat. The sensor placement depends on the way that a particular chemical behaves combined with the environment—such as an enclosed corridor or an open atrium—it protects.

That means before architects designate sensor locations, developers and construction teams must work together using a systems approach to identify potential terror scenarios and the chemicals attackers would most likely use. (See sidebar, "Imagining the Unthinkable.")

Tapping Existing Research

Although it wasn't part of their initial project plan, the MITRE team delivered a bonus for developers by incorporating existing MITRE—sponsored research that experts Susan Hanson and William Weiss had earlier developed to evaluate biological agent sensors.

"We were able to reach back to their research," Vu says. By uploading Vu's chemical sensor data, Hanson and colleague Michael Workman adapted the software to produce a chemical sensor selection tool (CSST). It allows users to choose detectors based on actual parameters, including costs.

"The end product is a list of sensors that meet the users' baseline requirements."

Applying the Results

With those tools in hand, "we hadn't yet identified an architectural space we could use in our study," Vu says.

The solution materialized during a chance meeting between David Dlugolenski, senior manager of emergency management for the Port Authority of New York and New Jersey (PANYNJ), and Charles Laljer, a MITRE multidiscipline systems engineer supporting the DoD Joint Program Manager for Nuclear Biological Chemical Contamination Avoidance, and subject matter expert on the MITRE ACVDS Technical team.

Laljer and Dlugolenski discussed MITRE's work for DHS S&T. "I knew Chrissy needed to apply her findings to a representative building, and the work David had at the World Trade Center was perfect for that," Laljer says.

As a result, PANYNJ invited Vu and her project team to a meeting of its DHS World Trade Center Chemical Biological Radiological Working Group. The team toured the World Trade Center site, including the site for the Port Authority Trans-Hudson (PATH) Transportation Hub, scheduled to open in 2015.

Considered the most striking architectural element of the World Trade Center complex, the soaring structure features 150-foot-high glass and steel "wings" through which natural light passes to the rail platforms 60 feet below. Its multi-story hall features stores and restaurants along a pedestrian concourse and tunnels connecting it to adjoining New York City Transit subway stations.

In the subsequent discussions with PANYNJ, MITRE shared its research findings, which used the PATH structure as a case study. The study factored in the building's design, use, environment, and surroundings when providing best practice recommendations for detector placement.

Through Vu's efforts, Senf says, "we created strong professional relationships within MITRE, delivered what our sponsor asked for, and developed a great working relationship with the PANYNJ."

Now that the study is complete, it won't just sit on a shelf. The information it contains provides independent verification of DHS S&T research about chemical, biological, radiological, nuclear, and explosive (CBRNE) threats, and helps set the stage for national standards, Vu says.

The National Strategy for CBRNE Standards takes a strategic look at the U.S. policy for the acquisition of chemical and biological detection equipment. "ACVDS delivered on a more tactical level," Laljer says, "focusing on the needs of first responders, such as police, emergency medical teams, border security officers, and park service staff."

Vu says, "We believe that the ACVDS outcomes will have long-term, positive impacts for years to come."

—by Molly Manchenton

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