There are currently 3 primary materials used in PPE:
- Barrier membranes (some with and some without textile layers)
- Filter textiles
- Basic textiles
- Missing: Self Decontaminating non-barrier textiles
The barrier membrane textiles are use naturally to prevent liquids from penetrating the Personnel Protective Equipment (PPE) ensemble. The barriers must be competent to prevent liquids containing viral particles from penetrating. The ASTM 1671 is the most common test criteria for these materials. Under the 1671 criteria the membranes must be capable of preventing viral penetration at 2psi or 54 inches of water pressure. As a result of this rigorous requirement the barrier membranes used in healthcare have limited moisture vapor transport. With low moisture transport from the ensemble the ever present heat stress risk in PPE becomes a serious issue in “Ebola type” treatment environments. The reason is in high infection risk Ebola treatment we currently have high PPE coverage using barrier textile materials. Cooler work environments are helpful never the less work sessions wearing high coverage barrier garments must be short, 2 hours or less in many situations. Healthcare workers must move ~150 watts of heat in order to maintain core body temperatures. As barrier membrane coverage area goes up workers in PPE find that they are not able to move there metabolic heat out of the ensemble.
Filter textiles are well accepted in healthcare, the N95 mask is a good example. This air filter requirement defines a textile that traps 95 of small <1 micron particles in the respiratory air flows. The limit of 95% is based on the need to limit respiratory effort. If the capture rate is higher the filter creates unacceptable restrictions to breathing because of the pressure drop over the filter materials. battery powered air pumps can be used to overcome the pressure drop from higher capacity filters. This down side is these powered full face filter units are not disposable and must be decontaminated manually after each use.
Basic cotton and poly-cotton textiles are ubiquitous in Healthcare. Scrubs and many other garments are used in PPE, hoods and other articles.
Self-Decontaminating Non-Barrier Textiles enable some really important new healthcare PPE solutions. The use of Self-Decon materials improves the thermal transfer of the PPE system. A significant reduction in heat stress can be achieved. The kill speed of the material in decontamination is important. We have now achieved 99.9% pathogen kill in 30 seconds and 99.99% in 90 seconds. So modern Self-Decontaminating textiles can be used to provide protection on high risk services. At the same time reducing the heat load for the healthcare worker. Like all PPE materials there are limits to the application of Self-Decon Textiles. They should not be used in the splash zone on the front and arms of the ensemble. Like the N95 mask the Self-Decon material can be used where splash risk is low. This provides the opportunity to build PPE ensembles that have 50-60% of the area with good moisture vapor transport for lower heat stress. At the same time these materials provides a lower stress garment the safety of healthcare workers are not compromised because the material provides pathogen self-decon in 30 sec.
Take a look at our self-decontaminating gloves for a good introduction to how these textile tools can help solve your PPE challenges. http://www.turtleskin.com/