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Scientists Search For Solution to PPE Sterilisation

The Covid 19 pandemic has created not just a public health crisis but a serious problem of waste disposal.

Most types of personal protective equipment, like N95 masks, gowns, and gloves, are designed for single use. This has led to both scarcity and waste during the pandemic.

In Scotland those providing care at home for a person with symptoms of Covid 19 have to place PPE in a disposable bag and then a secondary disposable bag when removed. It is then tied and held for 72 hours before being placed in the household bin for collection.

Thousands of tons of waste is being generated every day by PPE in household, care home and hospital settings.

Scientists in the USA are researching the possibility of sterilising all forms of PPE – like masks, gowns etc so that they can safely be reused.

It has long been known that ionized gases called plasma, which are made up of charged molecules, can kill pathogenic bacteria, viruses, and some fungi.

What was not known was whether or not PPE would work afterward if sterilised in this way.

David Staack and his team at Texas A&M University have now presented their preliminary data at  the American Physical Society’s Gaseous Electronics Conference.

The researchers tested three different types of N95 masks and found that two of them remained usable, even after being subjected to a sterilization dose of the low-temperature plasma. A 90-minute cycle in the decontamination chamber can kill 99.9% of microbes, including coronaviruses similar to SARS-CoV-2.

The team also looked at sterilisation with various doses of radiation using electron beams. These were effective at sterilisation but degraded the masks and gowns which meant they couldn’t be reworn.

Also looking into this issue is a group of researchers led by Lorenzo Mangolini from the University of California, Riverside. They looked at a low-cost approach to sterilizing PPE. The scientists repurposed a plasma ball–the inexpensive toy that seems to produce lightning in a small glass sphere–to generate ozone, which is carried by a jet of compressed air through a facepiece respirator. In proof-of-concept experiments, this approach successfully killed pathogenic Escherichia coli, which, because of its sturdy cell walls, may be more difficult to eradicate than viral particles like those of SAR-CoV-2.

Many more studies are being conducted worldwide at this growing mountain of waste problem. For the general public who are adhering to the advice on wearing face masks/coverings a reusable mask is the best way to reduce the waste. For PPE , however, a solution needs to be found for what is becoming a serious issue and a major pollution problem.

Reporter: Fiona Grahame

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