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http://hdl.handle.net/1947/9991
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| Title: | Study on Aerosol Penetration Through Clothing and Individual Protection Equipment. |
| Report number: | DSTO-TR-2283 |
| AR number: | AR-014-513 |
| Classification: | Unclassified |
| Report type: | Technical Report |
| Authors: | Roberts, M.
Jamriska, M.
Skvortsov, A.
McCallum, R. |
| Issue Date: | 2009-05 |
| Division: | Human Protection and Performance Division |
| Abbreviation: | HPPD |
| Release authority: | Chief, Human Protection and Performance Division |
| Task sponsor: | LWDC |
| Task number: | 07/076 |
| File number: | 2008/1104941 |
| Pages or format: | 32 |
| References: | 7 |
| DSTORL/DEFTEST terms: | Protective clothing
Aerosols |
| Other descriptors: | Individual protective equipment
CBR
Aerosol modelling |
| Abstract: | Aerosol particles can readily penetrate through air permeable fabrics. Air flow and aerosol deposition models were used to determine the skin deposition rates of aerosols through up to two fabric layers. These models were used in conjunction with a plume dispersion model to examine the risks associated with wearing air permeable CBR protective clothing, to inform IPE fabric development programs and allow assessment of aerosol protection requirements. |
| Executive summary: | Aerosol particles, either liquid or solid, behave differently in air flows when compared to gases and vapours. Gases or chemical vapour are captured by the activated carbon adsorbent in air permeable protective fabrics, however aerosols can couple to air flows which can carry aerosols through the porous structures of air permeable fabrics.
Air permeable chemical protective fabrics are used in both in-service chemical biological radiological (CBR) protective garments; the MkIV Overgarment and the low thermal burden black chemical biological (CB) suit. The level of risk associated with plume dispersed CBR aerosols (those released outside and carried by the wind) was quantified by modelling the amount of aerosol which penetrated IPE and deposited on the skin. This risk level will then inform IPE fabric development programs and allow assessment of aerosol protection requirements.
A software program was developed using simple air flow and aerosol deposition models to evaluate the threat posed by aerosolised agents through up to two layers of clothing. Three relevant clothing ensembles were evaluated using the models; the MkIV Overgarment, the black CB suit with DPCU shirt underneath, and black CB suit as a standalone garment. As the clothing layers were highly complex, fabric characteristics were generated by fitting an aerosol penetration model to experimental data of aerosol penetration through fabric swatches.
Results showed that the volume of air that flowed through the fabric layers was relatively small, which limited the total amount of agent which could move through the fabric and deposit on the skin. Additionally, the deposition rate of particles on the skin was low for the particle sizes that penetrate the fabric, as the physics that allows aerosols to penetrate through fabrics, also couples the aerosols to the air flow as it exits. This means that even though the fabrics had a high penetration of aerosols during swatch tests (of up to 95% of particles), less than a few percent deposited on the skin.
To show the risks associated with the aerosol penetration and deposition on the body, two highly engineered, weaponised aerosol threat scenarios were evaluated, using plume dispersion modelling.
Both scenarios demonstrated that respiratory protection is paramount against aerosolised threats, as deaths would occur in both cases without any protection.
Scenario 1 was a release of 50 kg of an aerosolised nerve agent, and modelling predicted that when wearing any of the three clothing ensembles, the dose deposited on the skin would be well below the assumed LD50 level. |
| Appears in Collections: | DSTO Formal Reports
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