"They protect us, we protect them."

Protective garments against chemical and biological hazards : standards, applications and text explanation

In the field of CBRNe these garments protect from war chemical weapons (many chemicals in different physical forms), and biological threat agents (microorganisms).
Then, it is natural to define tests to characterize the protective capabilities of clothing (test methods) and interpret the results (performance levels). However, we don’t have to forget that the garment are worn by someone whose physiological and psychological properties can be changed by wearing these PPE.

The personal protective equipment are designed to protect workers from occupational hazards. Their performances are measured with standards, depending on the usage scenario: Word explanation and questions.

The categories of PPE
There are 3 categories of PPE.
Category I. The company or reseller provides a self-certification of the product. PPE are simple in design and the dangers have no significant impact (superficial lesions ...).
Category II. The product is marked "CE". These PPE are used when the hazards are more important (serious injury). An independent certifying body certifies that the PPE meets the standards.
Category III. When danger is deadly, the product is in category III. It is marked "CE" and the company must apply a quality assurance or comply with an annual production control.

Chemicals protections
There are 6 types of protective clothing against chemicals
Type 1 gas proof clothing: NF EN 943-1
Type 2 non gastight clothing: NF EN 943-1
Type 3 Protection against liquid chemicals as a jet: NF EN 14605
Type 4 Protection against liquid chemicals as sprays: NF EN 14605
Type 5 Protection against solid particles suspended in the air: NF EN ISO
Type 6 Time limited protection against chemical liquids splashes: NF EN 13034

Types 1 and 2 are encapsulated suits.
The suits that meet the requirements of the types 3 and 4 are liquid-tight for type 3, and mists-tight (spray type splashes) for Type 4. Type 3 products are particularly suitable for chemical industries in which violent projections liquid jet may occur. Type 4. The products are addressed to chemical industries and agriculture for the protection against phytosanitary risks sprays.

The liquid are repelled off the suits. Type 5 suits protect against solid particulate chemicals transported by air (toxic dust). It can therefore be used for the asbestos removal or the agricultural world during powdering operations. Type 6 PPE offer limited protection against accidental splashes of liquid chemicals. They will be found in the petrochemical or chemical industries, the laboratories or in farming communities.

For example, a Category III PPE, Type 5/6 is a suitable to protect against the deadly risks as toxic dust and time limited splashes of liquid chemicals.
Another Class III PPE, Type 4/5 protects against liquid chemicals sprays and toxic form of dust.

Protection against biological risks
The biological risk is difficult to determine. If it is obvious in the case of field CBRNe (biological weapons are well known), but it is relatively unknown in the case of agricultural professions, agro-food industry and industrial laundries in which potentially contaminates laundry are handled. Protection from biological risks consists in preventing the germ from reaching the skin and mucous membranes.

The standard which defines performance requirements for protective clothing materials against infectious agents is the European standard EN 14126: 2003.
It combines four methods of testing materials considered to be representative of risk situations

+ contact with contaminated liquids : penetration test with artificial blood (ISO 16603), resistance to penetration by viruses (ISO 16604);
+ contact with immersed contaminated solids: resistance to bacterial penetration (ISO 22610);
+ exposure to liquid aerosols: resistance to penetration by biologically contaminated aerosols (ISO 22611) (it seems that this test is abandoned but it is still referenced in the standard);
+ exposure to solid particles: resistance to penetration by contaminated dust (ISO 22612).

As for the 6 types of chemical protection there are 6 types of biological protection named type 1-B, 2-B gas-tight, 3-B liquid-tight, 4-B aerosol-tight, 5-B dustproof and 6-B protection against light sprays.
The artificial blood used to perform the penetration test (ISO 16603) is made of cellulose, dye, buffer and stabilizers. Its red colour helps to identify the liquid when it passes through the material. Different pressures are applied and the pressurization time is 5 minutes: the passage of blood is a function of the pressure and it allows to determine six classes: from class 1 (0 kPa), - in the cell test the pressure of the liquid is only the hydrostatic one - to class 6 under a pressure of 20 kPa.

The resistance test to penetration by viruses (ISO 16604) is the same as the foregoing, Phi X 174 phage (simulating HCV, HBV or HIV) replacing the artificial blood.
Resistance to wet process bacterial penetration consists in depositing a bacterial inoculum on textile and measuring the time of passage of bacteria by mechanical friction (the underside of the textile is in contact with an agar culture medium). The 6 classes are defined on the penetration times: Class 1 <15 minutes to Class 6 with a time greater than 75 minutes.

The resistance to the penetration by biologically contaminated aerosols is measured by spraying an aerosol containing bacteria on 2 nitrocellulose membranes: a control membrane and a membrane protected by the fabric to be tested. After the test, the bacteria are counted on the 2 membranes. The value of the ratio of penetration (in log) without/with test material defines three classes: Class 1; R> 1 (passage of more than 10% of bacteria through the test fabric), Class 2; R> 2 (passage of 1%) and Class 3; R> 5 (passage of 0.001%).

The resistance test to penetration by dust (ISO 22612) consists in measuring the passage of a mixture of talc and bacteria deposited and shaken on the fabric sample. We measure the passage of the bacteria and compare to the inoculum. For example, if we pulverized 100 000 bacteria and 10 000 passed through the textile, the ratio is 10% and the material is positioned in Class 1. For 1% passage, ie 1 000 bacteria of 100 000 the material is Class 2 and Class 3 allows the passage of one bacterium per 100 000 (0.001%).

For all these tests, the higher the number of the class, the better the performance.

The scale of biological risk
We have already discussed the levels of risks and microorganisms confinement levels

Protections are function of the level of risk: for levels 1 and 2 a simple cotton gown is enough to protect from germs. Gloves and eye protection are aimed at level 2 in cases of a particular risk: the receipt or processing of biological samples for example. To protect bacteria from group 3 (Security Level 3) clothing must cover the whole body, overshoes and gown are required. A garment such suit is appropriate, a respiratory mask and gloves complete the equipment (and protective goggles in case of special need).
Handling type 4 biological agents requires additional garments as space-suits inside which a positive air pressure circulates.

Biological protection protections
•microbiology laboratories (diagnostics, production ...), •agriculture (protection against pathogenic bacteria as Listeria, Coxiella and against many allergens (fungi ...)
• waste sector (veterinarians, wastewater, sewage ...)
• police, emergency services, forensic ...
• food industry ...

Special case of Ebola
In a previous article we talked about the Ebola outbreak. Viral particles are present in all secretions.

The protections currently used for the work in the field are completely waterproof and classified at the highest level of performance of EN 14126. All field workers highlight the extreme thermal discomfort of these suits (the internal temperature can rise up 50 ° C making it impossible to work more than 1 hour in hot countries). In addition, after beeing worn, PPEs are considered as DASRI and must be incinerated after use.

The problem is the same concerning the protection from chemicals. It is advantageous to wear an air permeable "filtering outfit" which allows the passage of air and sweat while protecting against toxic because of the presence of an active carbon inner layer. Then, the material is more comfortable thanks to the evacuation of the sweat. This is the case of the Polycombi, which can be worn 12 hours and that meets NATO standards AEP 38 for protection against chemical warfare agents in liquid, vapour or aerosol. It further provides protection against chemical splashes spray type (type 4) against toxic particles suspended in air (type 5), and resists penetration by dust contaminated with microorganisms (class 3).

Moreover, that Polycombi avoids the pumping effect previously studied (http://www.ouvry.com/CBRNe/tenues-filtrantes-pourquoi-une.html?id_rubrique=33&id_groupe= 3).
Washable 3 times it can be disinfected by a conventional washing with bleach. Because it is worn longer and washable 3 times it gives less waste.
It is therefore important to well identify the risks in order to be equipped with the adequate equipment. In this case, the phrase "who can do more can do less" is not valid when the human physiology and psychology become the bottleneck.

You can follow the link : http://www.ouvry.com/CBRNe/polycombi-r


Nov. 2017
Paris-Nord Villepinte


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