If you have loved ones who are immunocompromised or not yet eligible for a COVID-19 vaccine, you know the problem: They need to wear high-quality masks for safety, but the masks can be uncomfortable and make it hard to breathe.
Ongoing mask dilemmas, made worse by the lightning spread of the virus’ omicron variant, gave new urgency to the work of Gaurav “Gino” Giri, an assistant professor of chemical engineering at the University of Virginia. Giri’s lab at the School of Engineering and Applied Science is developing an alternative mask technology.
Giri’s team is patenting a process for turning ordinary fabrics into inexpensive, washable air filters that breathe as easily as plain cloth masks, but are much better at stopping fine particle matter and other airborne hazards. He and his colleagues at Hava Inc., the company he co-founded with UVA assistant professor of public policy Balashankar Mulloth, anticipate releasing their first run of 5,000 face masks with Giri’s technology as early as March.
The team hopes that by then, the Hava masks will be certified under a new standard established in February 2021 by the American Society for Testing and Materials International for breathability and filtration efficiency. The standard applies to face coverings that are not medical masks or respirators.
N95 masks remain the gold standard in air filtration for personal protective equipment, filtering 95% of particles down to 0.3 microns in size – about 200 times smaller than the diameter of human hair. While the coronavirus is smaller than that at about 0.1 micron, it is typically attached to the water droplets or mucus we breathe out, which, like most particulate matter in air pollution, range from 1 to 4 microns or larger.
The U.S. Centers for Disease Control and Prevention advises that wearing highly protective masks such as N95s “may be most important for certain higher risk situations, or by some people at increased risk for severe disease,” but those types of masks “may be harder to tolerate or wear consistently than others.” The CDC guidelines state that for people who are not at increased risk and for non-medical situations: “It is most important to wear a well-fitted mask or respirator correctly that is comfortable for you and that provides good protection.”
While N95 masks are now widely available, Hava’s research revealed people overwhelmingly prefer cloth masks for breathability and comfort, Giri said.
The American Society for Testing and Materials’ specifications were developed in response to the COVID-19 pandemic to address what was a “Wild West of PPE” resulting from the lack of any standards for cloth masks, Giri said.
The standard sets two levels of certification for materials that filter tiny particles: Level 1 is 20% and above filtration, and level 2 is 50% and above filtration. In internal lab tests, using a polyester fabric for optimum softness and air flow, Giri so far has achieved greater than 40% filtration for coronavirus-sized particles.
The standard also sets two levels for breathability, determined by measurements of airflow resistance. The specified performance values are designed for the general public.
“Both levels require a lower filtration efficacy but have a more stringent standard for breathability than the standards required for N95 masks,” Giri said. “To our knowledge, there are very few masks that are fabric-based, without extra insert filters, that pass the ASTM level 1 standard, and none that are fully washable and reusable.
“Currently, our masks pass level 1 in both standards at lab scale. With this initial run of 5,000 masks, we are trying to show that large-scale production also passes these standards.”
Long before the COVID-19 pandemic, Giri and his team, including recent Ph.D. graduate Luke Huelsenbeck, whose name is also on the patent, began working on the process to coat textiles such as cotton, bamboo and polyester in solutions made with chemical compounds called metal-organic frameworks. The textiles are immersed in the solution, and the “MOF” particles grow on the fibers.
“MOF material is highly porous, but the holes are small enough to prevent particles from passing through,” Giri said. “Combined with chemistry that can stop harmful gases, the masks will be much more protective than plain cloth. The patent is about making the MOFs in a manner that can allow for rapid production, which is required for manufacturing masks, and can tightly integrate with a surface. This knowledge can be utilized for scaling up MOF production for any other application, too.”
The manufacturing techniques Giri developed enable the metal-organic framework material to form within and on the fabric, so it is not easily removed by washing. He has been using the Dyeing and Finishing Pilot Plant at North Carolina State University’s Wilson College of Textiles to performance test and produce the MOF-treated polyester material on large rolls.
A third-party vendor will take the rolls of treated fabric, cut and sew the masks, and package the masks for sale. Nick Cienski, Hava’s newly hired chief business officer, will oversee this part of the process. Cienski has an extensive history developing performance clothing and most recently was a principal in the innovation department at Under Armour.
The idea for developing the metal-organic framework fabrics came to Giri when he returned to Nepal, where he lived until age 14, for his wedding in 2016. The air quality in Kathmandu, situated in a Himalayan valley where the terrain traps pollution, was much worse than he remembered.
Nepalis wore face coverings, but he knew the inexpensive cloth masks most people could afford weren’t enough to protect against fine particle matter, especially from vehicle exhaust and wood smoke. At the time, he was already working with metal-organic frameworks, which are easy and cheap to produce in the lab. He suspected the new material could dramatically improve the air filtration power of masks people already were used to wearing.
According to the World Health Organization, 1.8 billion children around the world breathe air that puts their health and development at serious risk – and not all of them are in the developing world. The WHO’s director general, Tedros Adhanom Ghebreyesus, has called air pollution “the new tobacco.”
Through Hava Inc., Giri may eventually license the technology to manufacturers of items that people need and use anyway, such as scarves, hijabs, face masks and window curtains, to protect against dangerous pollutants – or contagious viruses. Because Giri’s metal-organic framework coating is applied similarly to how fabric is dyed, his method can be integrated into existing industrial textile dyeing processes.
“All of this is possible due to the rapid manufacturing of MOFs described in the patent,” Giri said.
The idea is to tailor personal air filtration products to users’ specific needs and cultural preferences.
“In places like Kathmandu where outdoor air quality is often unhealthy, and at times hazardous, people need effective protection they can afford. If the products fit seamlessly in their day-to-day lives, the hope is they’ll use them consistently,” Giri said.
“But air quality is a problem in the United States, too. For the past few summers, Americans have been affected by wildfires in California. And if we can show that our material really does filter the SARS-CoV-2 virus and doesn’t restrict breathing, we might be able to overcome some people’s reluctance to wear face coverings in public settings.”