Defence Science and Technology Organisation (DSTO) is a national leader in safeguarding Australia by delivering valued scientific advice and innovative technology solutions for Defence and national security. DSTO’s chemical, biological, radiological and nuclear (CBRN) research aims to effectively prevent, respond to and defend against CBRN attacks in military and civil environments.
To this end, one focus of the DSTO research program is to provide protection for individuals from unavoidable CBRN hazards. Current CBRN individual protective equipment (IPE) provides high levels of protection for long periods of time, having been designed to meet requirements originally perceived for military cold war threats. These garments impose a high thermal burden on the wearer, and can constrain user functionality and mobility. As such, user workloads are reduced and mission completion times are increased.
Reducing the burden associated with CBRN protective clothing would improve mission outcomes in a CBRN environment. As such the DSTO focus is to provide greater operational ability, to optimise the balance between protection and burden.
What do we mean by low burden? Burden can mean ergonomic/system integration/thermal/situational awareness. All are affected by CBRN IPE and there is traditionally a trade-off between protection and burden. For example, high protection is relatively easily achieved in Level A Self Contained Breathing Apparatus (SCBA) equipment, but users can only operate for a short period of time. Current military CBRN IPE allows users to work for longer than Level A equipment; however CBRN ensembles still provide significant impediments to operational capability when compared to standard uniforms. Particular issues include reduced heat transfer ability through wearing heavy, bulky over garments, over boots which are cumbersome, bulky gloves which reduce tactility for fine motor tasks, and respirators which reduce field of view and communication ability. Functional requirements for low burden IPE garments can be defined as: light weight, low thermal burden, ease of movement and low bulk materials.
Modelling of current scenarios shows that high challenge levels are still possible, however exposure to these high concentrations is likely to be for short periods of time, for both military and civil response users. Longer term protection, if required, will be against much lower concentrations. Additionally, CBRN IPE has historically focussed on liquid and vapour threats, and the inclusion of aerosol protection would improve protection for users.
These changes in scenarios have caused DSTO to reflect on user requirements for IPE and to articulate what low burden IPE means in the current and future environment. This has allowed DSTO to develop a clearer understanding of the requirements for modern IPE and to develop innovative programs for delivering low burden IPE through the application of novel materials. This two pronged attack allows DSTO to focus on the delivery of low burden IPE with both a requirements focus: what does the user need to be able to do their job effectively; as well as from a science perspective: what is achievable and possible from IPE fabric and materials systems. Combining this holistic approach with high value test and evaluation capabilities allows DSTO to deliver high quality research into low burden IPE solutions for the ADF, an approach easily transferred to civilian first responders.
To produce effective low burden IPE that provides a significant improvement on current ensembles in terms of thermal and operational performance, fundamental questions need to be answered:
What are the likely dermally relevant challenges that users might experience?
Using plume dispersion models, like the US-developed Hazard Prediction and Assessment Capability (HPAC), with inputs from meteorological data, urban models and terrain models DSTO can predict the results from specific outdoor CBRN releases. The data generated includes the extent and spread of the challenge, how it spreads in the environment, what proportion of the contaminated area has “high” or “low” concentrations and how long the hazard remains in the environment. The HPAC plume modeling provides a predicted average value for outdoor releases.
Dispersion modeling can also be used to predict challenge levels for indoor releases. The models used generate a timeline, which demonstrates that concentrations experienced at a single location are often highly variable. The maximum concentration achieved and the length of time that high concentrations persist are more important than simple average values when it comes to determining the protection required for people exposed to that environment. Using time resolved protection requirements allows DSTO to tailor the protection provided by the protective materials, optimizing protection.
Concept of operations: how long must users remain in IPE, endurance requirements, and work rate requirements
By combining the CBRN challenge predictive capability with war gaming (operations research) detailed effects on the user population can be determined. This is extremely useful for performing trade-off studies such as determining appropriate protection levels required, and what levels of heat stress might cause missions to fail. This allows DSTO to test scenarios which are difficult or impractical to assess with field trials, and feeds back valuable information about protection requirements and thermal burden trade-offs in scenarios that users could be expected to experience on the ground. It also allows DSTO to target physiological experiments to provide the best data available with minimal resources.
Once these questions have been answered, this defines what the users need or desire. Within the limitations of current technology DSTO (and more broadly Defence) then has a clear basis from which to develop requirements for low burden IPE that can provide a significant improvement in capability for users.
A parallel approach is to take scientific concepts and determine how effective they are at providing protection; this allows scientists to take innovative approaches to solve the problem. For example for IPE material concepts: if we make a fabric with particular properties what would it look like? How well will it provide protection? How well will it perform in an operational environment? DSTO can evaluate the gain in performance versus the protection and how this compares to those options generated from the requirements studies.
Science driven concepts also allow us to determine where the knowledge gaps are. With specific designs, how would we make them work, what future investigations for different components are needed? What is possible, what is improbable/too far-fetched?
Two different developments at DSTO highlight laboratory work which showcase the requirements driven (systems testing) and science driven (novel materials development) aspects of our work.
Novel Adsorbent Fabric
DSTO is investigating an innovative nanofibre membrane concept as an alternative to activated carbon cloth/scrims in protective clothing. In current technology suits, combined aerosol and vapour protection can only be delivered through air impermeable membrane materials which cause significant thermal burden. DSTO is investigating a lightweight aerosol filtration membrane made from nanofibers. These nanofibers are generated with adsorbent media inherently embedded in the fibres, to provide protection against vapour challenges.
Proof of concept work has shown that this composite membrane can successfully remove vapour and aerosol challenges from the airstream, while providing some air permeability. DSTO is now advising the Defence Materiel Technology Centre on the progression of this technology from the research concept stage.
New evaluation systems
Being able to effectively measure the protection and performance provided by low burden IPE is critical to its success. To that end, DSTO has a suite of tests available to measure the performance of IPE. We can effectively measure the relative thermal performance of different IPE systems through fabric swatch testing, and thermal manikin testing to evaluate expected thermal burden and translate this information into the loss of capability or functionality for the user. Chemical protection capabilities of the materials can be tested in purpose built facilities against target chemicals of interest. However fabric swatches only provide part of the story, as extremely effective fabrics do not make extremely effective suits unless the design is right and closures and seams minimise leakage gaps. DSTO’s manikin test facility is currently being validated and will provide system level detail on the protection capabilities of suit systems and integration of IPE.
Current international best practice systems testing of this type measures end point skin exposure values, which provides the cumulative results of leakage under the suit at different points on the body across the entire program of manikin movements. DSTO has developed real time breakthrough measurement capability that allows scientists to monitor vapour challenges breaking through the suit, and to correlate the break through events with particular movements or exercises. This capability will add to the available data to determine causes of suit failures from either fabric, suit design or system integration issues.
The combination of fabric swatch testing and manikin testing for chemical and thermal performance provides DSTO with the ability to assess different IPE suit systems in detail, and to determine if IPE systems meet requirements. These results, combined with modelling of use scenarios allows DSTO to deliver advice on the most effective equipment combinations to optimise the trade-off between protection and thermal burden effects of CBRN IPE.
For more information, go to www.dsto.defence.gov.au