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Engineers devise low-cost way to decontaminate PPE equipment

Image credit: Eldar Nurkovic/Dreamstime

Researchers in the US have devised a scalable method, using widely available materials found in hardware shops, to decontaminate personal protection equipment (PPE) as the coronavirus pandemic continues.

With the winter months looming, the number of new coronavirus cases being reported in the US is rising. This mirrors Covid-19 activity already seen in Europe and elsewhere across the globe. Meanwhile, supply-chain problems are likely to cause limited supplies of filtering facepiece respirators, such as N95 masks. Yet strategies to decontaminate personal protective equipment, or PPE, remain unresolved in many hospitals with limited resources, in many countries.

To tackle these issues, researchers at the University of Delaware (UD) have developed a system for decontaminating N95 masks using off-the-shelf materials that can be purchased at hardware shops, combined with ultraviolet type C (UV-C) lights found in academic research and industrial facilities. The UD-developed method offers comparable decontamination to more expensive methods at an affordable cost of about $50 (£38) in materials.

“We focused on frugal science – how do you decontaminate PPE in a very simple way that is easily scalable for high throughput so that any health care facility can use it globally,” said Jason Gleghorn, an associate professor of biomedical engineering at UD. Frugal science refers to the design, development, and deployment of ultra-affordable yet powerful scientific tools for the masses.

The project was inspired by Rachel Gilbert, a doctoral candidate in the Gleghorn lab, after she learned that friends in the medical field were repeatedly donning the same N95 mask day after day. She knew that UV-C light was routinely used for sterilisation of various materials and equipment found in research labs and wondered if this technique could be repurposed to decontaminate specialised masks, specifically for front line workers, in a low-cost, scalable way.

“Being able to provide something that can be on-site, as opposed to other methods that require surgical-suite UV systems costing tens of thousands of dollars or shipping masks out for decontamination and relying on them coming back in a timely manner, was important,” Gilbert explained.

The system the research team constructed modifies common fluorescent light fixtures to hold and power the specialised UVGI light bulbs. That, in addition to specific light placement arrangements and tin foil covered cardboard for reflectors, creates multiple decontamination arrangements people can make. 

To confirm the UV-C lights were effective, the researchers did copious mathematical calculations and modelling to ensure the intensity of UV radiation that the repurposed lights emit was correct and the N95 masks received the correct UV exposure to decontaminate the masks.  

The team then developed an instruction manual, which emphasises UV safety and focuses on use in healthcare because of the need for specialised equipment, such as a UV-C-intensity meter. They also include precautions to measure UV-C intensity to ensure confidence the system is delivering the correct degree of UV intensity for enough time to decontaminate.

The researchers stressed that the method is not an at-home device. “You need proper personal protective equipment to work with UV light, which can disrupt DNA and pose safety concerns,” said Gilbert. This disruptive feature, however, is exactly what makes the UV-C light useful for decontaminating PPE, the team said.

“The UV light causes the virus DNA to break up and become ineffective,” explained Gleghorn. “So, the virus – that little spiky thing you’ve seen by now – might still stick to you, but the genetic material inside will be fragmented and will not have the correct machinery to replicate.”

Kim Bothi, executive director of UD’s Center for Hybrid, Active, and Responsive Materials, said: “Like any other technology or innovation, our off-the-shelf decontamination method will only have an impact if people are aware of it.”

The researchers concede that mask re-use is not ideal, but they also recognise that not all hospitals or other patient care facilities are equipped with enough PPE to meet demand in a crisis, so first responders may be required to reuse masks in emergency situations. 

Bothi would like to see academic and research institutions working hand-in-hand with hospital systems to collaboratively put these off-the-shelf systems in place where they are needed. 

Kenya, for example, is a country in sub-Saharan Africa that has a fairly robust system for healthcare. Yet, the country is still facing incredible shortages of PPE similar to the US. “The bigger benefit will be translating this to other areas of the world, where they don’t have the resources,” said Gleghorn.

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