Challenges for Chemical and Biological Protection

FUTURE SCENARIOS WILL LIKELY INVOLVE DIMINISHED QUANTITIES OF AGENT, BUT DEPLOYED IN UNEXPECTED PLACES THROUGHOUT THE DEPTH OF THE THEATER OF OPERATIONS USING IMPROVISED WEAPONS.

The fall of the Berlin Wall almost two decades ago signaled the close of the Cold War, and yet the approach to current capabilities for individual and collective chemical and biological protection has not significantly evolved. The character of the threat has evolved beyond scenarios of tons of agent per hectare proceeding armored assaults on a linear battlefield.

Future scenarios will likely involve diminished quantities of agent, but deployed in unexpected places throughout the depth of the theater of operations using improvised weapons. Threats may include classical CB agents, as well as nontraditional agents and emerging biological threats. It also can include toxic industrial chemicals/toxic industrial materials (TIC/ TIM) that could threaten operational forces through accidental or malicious release.

As a consequence, risk may be rising. Protective equipment may not have to defend against the same quantities previously established as the standard, but will have to address a broader spectrum of agents. Further, the nature of the threat may require greater availability of protection that is built-in, rather than added on, vehicles, vessels, platforms, structures and standard battledress. Protection that is always present will be available when needed. However, constant availability is only practicable when it does not increase the burden on the warfighter. Meeting the challenge of lowering the burden is the focus of science and technology efforts within the protection capability area.

CHALLENGES
 
The Joint Science and Technology Office for Chemical and Biological Defense (JSTO-CBD), which is operated within the Defense Threat Reduction Agency’s (DTRA) Chemical Biological Technologies Directorate, has the responsibility to develop and manage the technology base for chemical and biological passive defense capabilities. This technology base feeds the acquisition programs managed by the Joint Program Executive Officer for Chemical and Biological Defense (JPEO-CBD) in support of user requirements.

User issues with current protective systems focus on factors such as burden, costs, duration of performance and effectiveness against a full range of agents. These operational challenges translate to the development of materials and systems that capture, block or destroy agents more effectively than the current systems.

These technology solutions must also decrease material weight and costs, while reducing burden and lessening the impact on mission performance. Specific challenges are subdivided below in the technology theme areas of air purification, material science, human performance and systems science.

AIR PURIFICATION

Removal of hazardous low-molecular weight chemical vapors, which include some of the most common TICs, has been the limiting performance characteristic of technologies based on impregnated activated carbon. The primary challenge is to develop broad spectrum treatments, while reducing size, flow resistance, and power demand.

Particulates and aerosols have increasingly become important considerations for both biological and chemical threats, but current high efficiency particulate air technologies create significant pressure barriers (pressure drops) to airflow and have diminished performance for the smallest particles. Additionally, these traditional approaches have limited service lives and thus impose a significant logistical burden in replacements.

MATERIALS SCIENCE

Barrier materials used for protective clothing impose a thermal burden. The balance of maximizing protective performance while minimizing thermal burden has been the essence of the challenge. The need to protect against particulates and challenges further complicates the issue.

Self-detoxifying materials are seen as a means of increasing service-life and performance, while simultaneously decreasing thermal burden, but these materials need to be safe, shelf-stable, and effective against a broad spectrum of potential agents.

HUMAN PERFORMANCE

The burden and degradation of mission performance is the warfighters’ primary issue with currently fielded individual protection systems. Burden and mission degradation are based on a multitude of both cognitive and physiological factors. Some factors such as heat burden are well quantified, but others such as cognitive effects of encapsulation are not.

SYSTEMS ENGINEERING

Currently fielded and developmental individual and collective protection still use a variation of a basic design derived many decades ago. Whole system analysis is needed to determine the value of new and emerging technologies that may allow a revolutionary systems approach to individual and collective protection.

APPROACHES

Low-Burden Individual Protection

Present investments have focused on the development of the separate components that will feed into a complete Joint Chemical Ensemble (JCE). Traditionally, protective masks and protective clothing have been developed as separate programs based on separate requirements documents. JCE, however, will proceed as an integrated concept. A holistic approach can balance various elements such as power demand, mission interface and thermal burden.

As a concept refinement strategy, thermal performance can be managed as an independent variable by setting the desired thermal load equal to that of a standard battledress uniform (such as the Army combat or Marine disruptive pattern uniforms), then determine the best achievable chemical/biological performance under that constraint. This is a similar approach adopted in the Canadian technology demonstration titled CBPlus. Such an approach does a better job at spurring technological innovation and will provide the user with a better understanding of the tradeoffs between performance and physiological burden.

Much of the cognitive burden and mission degradation lies in the interface between the chemical/biological protective ensemble and the balance of mission equipment. The chemical/biological protective ensemble must integrate with ballistic protection, optics and communication.

The interface of the current protective mask with the helmet accounts for a number of issues. Problems include disrupting the helmet suspension system, potentially compromising the seal of the mask, and the creation of irritating “hot spots.” Early integration between these systems must occur during concept refinement and technology development.

An integrated chemical/biological ensemble that is a component or accessory to an integrated warfighter system, like the Army’s Ground Soldier System, may be the desired outcome. Achieving low-burden necessitates the innovative application of new technologies.

A number of new technologies offer considerable opportunities in achieving integrated low-burden protection within a broadening threat spectrum without compromising needed performance. One of the most exciting areas is reticular chemistry, which is described as the “linking of molecular building blocks of synthetic and biological origin into [a] predetermined structure using strong bonds.”

The most well-known class of these materials is metal organic frameworks which have already exhibited absorbency potentials that far exceed activated carbon, and are currently being manufactured in commercial quantities. These compounds can be tailored to target specific classes of chemicals that include the high volatility TICs which limit the performance of current technologies. Such compounds can be used to design smaller and lower-profile filter beds that protect against the expanding spectrum of threats.

Smaller and lower profile filters decrease weight and reduce interference of the respirator with other mission systems. Reticular chemistry has the potential to go far beyond this. Reticular structures could be designed to contain an internal catalyst that detoxified the agent, or structures could be designed to adsorb as well as detect the compound or agent adsorbed.

Another promising area has been the development of nanofibers. These fibers have diameters on the scale of the mean-free-path of an air molecule. When nanofibers are used as a filter media the aerodynamics are governed by the “slip flow” or Knudsen regime with much lower drag than conventional flows. This implies that it may be possible to produce particulate filters with order-ofmagnitude lower pressure drops, and high efficiency particulate filtration capabilities built into the clothing. In recent years, a number of innovations have just about made the production of these materials commercially viable.

Additional developing technologies will make it possible to assemble these fibers into nano-composites that will include builtin adsorption, reactive, anti-microbial, and sensing capabilities into a thin coating. This could revolutionize protective clothing, and produce unconventional and extremely low burden approaches to respiratory protection.

Intrinsic Collective Protection

Near-term efforts in collective protection are focused on the development of air purification technologies that address a broader spectrum of threats and reduce size, weight and power consumption. Additional projects support the development of new higher performance barrier materials.

However, these technologies support traditional system configurations. In order to make it truly universal, collective protection must be reinvented from a systems perspective. Efforts in collective protection will seek novel, low-cost and scaleable approaches that allow seamless incorporation into all building and vehicle designs, and support rapid (field) conversion of fixed facilities.

System approaches will be developed that allow less dependence on overpressure techniques and depend more heavily on network integration and rapid response. This will blur the distinction between shield and sustain functions. Technologies that include strippable coatings, self-detoxifying surfaces, and responsive (switchable) surfaces will be developed to support collective protection configurations that can rapidly mitigate fugitive internal contamination transfers.

Perhaps more important, intrinsic and universal collective protection may be more constrained by our thinking. Currently, collective protection must meet a challenge standard equivalent of being the target of a rocket barrage. A more flexible approach that identifies areas and points of specific vulnerability may be in order. Settling for less protection in lower threat areas can facilitate investments in lower-cost approaches. Lower costs allow for universal design of protection. This will enable a sufficient degree of protection to be always available and will likely reduce the overall risk.

CONCLUSION

Solutions to the challenge of low-burden protection depend on discovery, development and implementation of novel technologies. Of particular concern are technical challenges associated with the development of new materials. Only by leveraging other funded areas of research can success be achieved. This requires partnering with industry through Cooperative Research and Development Agreements, and developing and making use of cooperative agreements with allied countries.

Despite the difficulty and expense of developing new materials, the technical opportunities present today assure a good chance of success. The risks imposed by evolving nature of the threat demand the effort. ♦

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