Researchers say that they have developed an air filter that can capture SARS-CoV-2, the new coronavirus, and instantly kill it.

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A novel air filter made of nickel foam could capture and kill airborne particles carrying SARS-CoV-2.

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A new study outlines the development of an air filter that catches and instantly kills the virus behind the COVID-19 pandemic, SARS-CoV-2.

The study, published in Materials Today Physics, indicates that it may help reduce the spread of the virus in indoor environments.

As emergency measures responding to the first wave of COVID-19 begin to relax across the world, experts are turning their attention to how people can carry on with their everyday lives under the threat of a second wave.

One aspect of this is how to protect people in places where the virus can spread quickly, such as indoor spaces.

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The authors of a recent review think that people cannot only transmit the new coronavirus through infected mucus or saliva from coughing, sneezing, or talking but through bioaerosols (minute particles) generated through speaking or breathing.

Bioaerosols can also develop when droplets lose water and become a fine aerosol themselves, called droplet nuclei.

Aerosols are much smaller than droplets. Although scientists are in a debate about their size, they are small enough to become airborne. According to Dr. Mahesh Jayaweera and his co-authors of a recent article, SARS-CoV-2 bioaerosols typically measure less than 5 microns (μm) in diameter. In contrast, a droplet from a sneeze would measure 100 μm in diameter, while most respiratory droplets are 5–10 μm in diameter.

While droplets carrying the virus drop quickly to the floor, which allows the virus to live on surfaces that they come into contact with, aerosols stay suspended in the air, potentially transporting the virus farther away.

However, Dr. Jayaweera notes that there is not enough research to determine to what extent SARS-CoV-2 can do this. For example, while aerosols may carry the virus farther away, they might also be more susceptible to damage by environmental factors when transported in this way.

On the other hand, there is a growing scientific consensus that aerosol transmission of SARS-CoV-2 is possible. The World Health Organization (WHO) have recently updated its advice on transmission routes of the new coronavirus to include airborne transmission. However, the WHO is cautious about whether SARS-CoV2- in aerosols is viable and capable of causing infection.

Scientists need to conduct more research to fully understand how Sars-CoV-2 is transmitted and identify the best strategies and technologies for inhibiting the spread of the virus.

Conducting high-quality research takes time and depends on real-world data to be as accurate as possible. While data from the first wave of the pandemic are now becoming available, it still takes time to process these data and ensure any studies that draw on them are rigorous and meet traditional academic standards.

However, given the severity of the pandemic, there is an urgency to develop new technologies drawing on the best currently available evidence.

In this context, the present research gives an overview of a new filtration technology that captures the virus and almost instantly kills it.

Researchers from the University of Houston, TX, designed the filter in collaboration with the medical real estate development firm Medistar and researchers from other institutions.

According to the researchers, the nickel foam filter killed 99.8% of SARS-CoV-2 particles that passed through it.

The researchers heated the filter to 200ºC to achieve this. Previous research found that exposing the virus to 70ºC for 5 minutes deactivates it. At 200ºC, the filter can kill the virus immediately.

Usually, nickel foam has a low resistivity, which means it is difficult for it to achieve high temperatures. By folding the foam and using additional compartments connected with wires, the researchers were able to increase its resistivity and maintain the 200ºC temperature without needing external heating sources.

This is particularly important if the designers intend to insert the filters in air conditioning systems. By not requiring an external heating source, which could heat the air temperature, these filters become viable.

According to Prof. Zhifeng Ren, MD Anderson Chair Professor of Physics at the University of Houston and the co-corresponding author for the paper:

“This filter could be useful in airports and in airplanes, in office buildings, schools, and cruise ships to stop the spread of COVID-19. Its ability to help control the spread of the virus could be very useful for society.”

While researchers have shown that the prototype filter kills the vast majority of the virus that passes through it, they do not yet know its real-world effects in reducing transmission of the virus.

Until scientists have carried out more research to understand how the virus spreads and which method results in the highest transmission, they cannot determine whether filtration systems will make a difference.

Nonetheless, given the urgency of the current pandemic and the plausibility that aerosols can transmit the virus, having such technologies available is valuable.

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