Texas Tech University

Leading the Way

TTU professor Seshadri Ramkumar

Seshadri Ramkumar, a professor of chemical countermeasures and advanced materials at Texas Tech University, stands in the Chemical Countermeasures and Advanced Materials Lab he leads.

Seshadri Ramkumar Explains Differences Among Types of Face Masks

Rigorous Testing Is Needed, But There's Reason to Believe Nonwoven Cotton Might Enhance Filtration Capability of Common Face Covers


When it comes to blocking coughs and sneezes, any mask is better than none. But as the COVID-19 pandemic has illustrated so vividly, not all masks are created equal.

At a time when the most effective masks continue to be reserved for the most critical personnel, the Centers for Disease Control and Prevention (CDC) recommends everyone wear cloth face coverings in public settings, while also practicing 6-feet social distancing.

In a recently released 45-second video, U.S. Surgeon General Dr. Jerome Adams demonstrated how to make a multi-layered face cover from an old t-shirt and two rubber bands. Meanwhile, the Internet is flush with merchants selling face covers of all descriptions, some of which include a pocket to hold various types of filters.

In the midst of all of this, one Texas Tech University (TTU) scientist has spent much of his 20-year career studying personal protective equipment (PPE)—particularly nonwoven cotton substrates—and their effectiveness against a host of environmental and human-health challenges.

Seshadri Ramkumar, professor and supervisor of the Chemical Countermeasures and Advanced Materials Laboratory at TTU's Institute of Environmental and Human Health (TIEHH), developed the chemical decontamination wipe Fibertect®, which has tested highly effective in adsorbing certain chemical warfare agents, toxic industrial chemicals and pesticides.

During the Deepwater Horizon oil spill, his work proved the effectiveness of natural cotton as a crude oil absorbent. A more recent breakthrough is his work with Ph.D. student Lihua Lou in developing a nanofiber filter that, when combined with visible light, can remove toxic dye pollutants from wastewater safer, cheaper and easier than traditional methods.

Ramkumar explains the efficiency of any barrier-type mask—one that covers the nose and mouth—depends on its filtration capability, its fit and its form or comfort; and they all fall into four general categories:

  1. FFRs, or filtering facepiece respirators, such as the N95 mask;
  2. Surgical masks;
  3. Common face covers;
  4. FISORS, Ramkumar's designation for face covers that have enhanced filtration capability.

FFRs/N95 Masks

According to the CDC, COVID-19 is thought to spread person-to-person between people within about 6-feet of one another, through respiratory droplets produced when an infected person coughs, sneezes or talks. These droplets can land in the mouths or noses, or possibly be inhaled into the lungs, of people nearby.

Ramkumar says the intensity of transmission depends on the size of the virus and the load.

"It is well accepted that to counter the finer particles that easily diffuse through substrates, an FFR, commonly referred to as an N95 mask, is needed," he says.

Such masks are generally used in hospital isolation wards and where intubation is encountered. "The N95 is the first line of defense for doctors and for patients recovering from COVID-19," he says.

Surgical Masks

According to the U.S. Food & Drug Administration (FDA), surgical masks are fluid-resistant, disposable, loose-fitting devices that create a physical barrier between the mouth and nose of the wearer and the immediate environment. They often may be made of multiple layers of nonwoven material.

Because they are designed to serve as a barrier against bodily fluids such as blood, and not aerosolized particles such as viruses, Ramkumar says they, therefore, do not provide a level of defense equal to N95 masks.

Common Face Covers

These face covers may be homemade or manufactured and typically are constructed of common fashion fabrics of a consistent weave. Depending on the mask's structure and material, its ability to filter will vary, Ramkumar says; and he sees a need to improve their filtration capability.

FISORS/Masks with Enhanced Filtration

face cover with nonwoven cotton filter from Scarborough SpecialtiesBased on his success in using nonwoven cotton to decontaminate chemical spills and oil spill, Ramkumar has reason to believe that nonwoven cotton may enhance the filtration capability of common face covers—though he would be the first to say that rigorous testing of this hypothesis has yet to be done.

Depending on the specific purpose, FISORS, he says, may have multiple types of filter substrates.

"However, studies have shown that copper and cellulose fibers such as cotton do a better job than plastics in destabilizing viruses," Ramkumar says.

In fact, viruses have been tested on the surfaces of cardboard, stainless steel, plastic and nonwoven cotton. Ramkumar says those tests showed that viruses did not remain stable on cotton.

"Further, any structure that presents a challenge to direct airflow may serve as a better filter," he says.

The smaller pore size and random arrangement of fibers in nonwoven materials presents exactly such a challenge.

a face mask containing nonwoven cotton from Arrow BroguesNot surprisingly, the same Nonwovens and Advanced Materials Laboratory that developed Fibertect® recently collaborated with two Lubbock businesses—E Innovate, LLC, and Scarborough Specialties, Inc.—to develop a face cover with a pocket for a nonwoven cotton filter. Ramkumar is collaborating with India-based Arrow Brogues, Pvt. Ltd., a fashion shoe manufacturer, in designing new face masks.

During the height of the COVID-19 pandemic, Ramkumar's outreach transcended both borders and shelter-in-place directives via educational webinars on personal protective textiles that, so far, have attracted more than 500 participants from India, China and Canada, in addition to the United States.

Recently, Ramkumar discussed nonwoven cotton filters during an on-camera interview by Lubbock television affiliate FOX-34 and in an opinion column published by the Lubbock Avalanche Journal. He also has recorded a Facebook video for India-based Life Again Foundation and collaborators for its Mask Marathon Campaign.

While no one is making any medical claims about these face covers, Ramkumar says simply, "Something is better than nothing. We didn't invent anything new. We just connected the dots." 

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About the Nonwovens and Advanced Materials Laboratory

The Nonwovens and Advanced Materials Laboratory founded by Seshadri Ramkumar has been carrying out research with nanofibers and advanced fibrous materials for two decades. Early work included the creation of FiberTect®, a nonwoven decontamination wipe capable of cleaning highly toxic chemical agents. More recent work has involved the development of environmentally friendly oil absorbent wipes and the incorporation of natural biocides in nanofibers to develop materials that can be used in wound healing.

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