Date Published: February 8, 2019
Publisher: Public Library of Science
Author(s): Min Li, Jennifer L. Furlong, Patrick L. Yorio, Lee Portnoff, Athanassia Athanassiou.
Protective clothing manufacturers routinely test their products for resistance to liquid and viral penetration. Several of the test methods specified by the American Society for Testing and Materials (ASTM) and the International Organization for Standardization (ISO) for penetration testing produce binary results (i.e. pass or fail), deliver imprecise pressure regulation, and do not record the location at which penetration events occur. Instead, our approach measures a continuous variable (time of penetration) during a slow and continuous increase of hydrostatic pressure and retains the location of penetration events. Using a fluorescent dye to enhance visual detection, we evaluate temporal and spatial patterns of penetration events. We then compare the time of liquid penetration with the time of penetration of two bacteriophages (Phi-X174 and MS2). For the fabric tested, the mean viral penetration occurred 0.29 minutes earlier than liquid penetration when solved by logistic regression. The breakthrough time of MS2 was not different from the Phi-X174 bacteriophage. The time of liquid penetration was a latent indicator of the time of viral penetration.
Healthcare personnel (HCP) have an increased risk of exposure to disease from close contact with infected patients . During medical procedures and routine visits, pathogens contained in a patients’ body fluids (e.g. blood, saliva, urine, feces, or vomit) may lead to infection of HCP. One possible means of exposure to infectious body fluid is by penetration through protective clothing (e.g., surgical gowns).
Temporal analysis showed a non-normal distribution of liquid penetration times between 8.15 to 11.18 minutes (n = 78). An ideal material containing equal-sized pores would have a normal distribution, while irregularities, imperfections, or calendaring the fabric may result in additional failure modes. The test apparatus itself may also cause pinching or stresses on the fabric that could result in early failures. The fabric tested had 83.4% (λ = 0.834) uniform structure with 16.6% (λ = 0.166) early failures. The magnitude of each distribution mode (83.4% and 16.6%) indicates that this fabric is mostly uniform but contains one-in-five premature failures.
This paper presented a quantitative approach to evaluate a fabrics’ resistance to liquid and viral penetration. To our knowledge, it is the first paper to compare the time of liquid penetration to viral penetration. Testing estimated that the difference between liquid and viral penetration was 0.29 minutes for this fabric. Further evidence of the ‘viral compatibility’ between the liquid and viral test for this fabric may allow the manufacturer to substitute an inexpensive quick screening technique for a costly viral test.