Both the World Health Organization and the U.S. Centers for Disease Control recognize that aerosols are the primary mechanism for the spread of the COVID-19 virus. Aerosols are tiny particles of water or other substances that can remain suspended in the air for long periods of time, small enough to penetrate the respiratory system.

People release aerosols when they breathe, cough, talk, shout or sing. These aerosols can also contain the virus if they are infected with COVID-19. Inhaling sufficient quantities of coronavirus aerosols can make a person sick. By requiring people to wear masks, improving indoor ventilation and air filtration systems, reducing personal exposure and reducing the total amount of aerosols in the environment are priorities for curbing the spread of COVID-19 aerosols.

Research on infectious new viruses is dangerous, and is relatively rare in laboratories with the highest levels of biosafety. All studies to date on masks or filtration efficiency during the pandemic have used other materials thought to mimic the size and behavior of SARS-CoV-2 aerosols. The new study improves on that, testing aerosolized saline solutions and aerosols containing a coronavirus from the same family as the virus that causes COVID-19 but only infects mice.

Yun Shen and George Washington University colleague Danmeng Shuai created a nanofiber filter that delivers a high voltage through a drop of polyvinylidene fluoride liquid to a spinning thread about 300 nanometers in diameter—about 167 times thinner than a human hair . This process created pores just a few micrometers in diameter on the nanofibers’ surface, helping them capture 99.9 percent of coronavirus aerosols.

The production technique, known as electrospinning, is cost-effective and can be used to mass-produce nanofiber filters for personal protective equipment and air filtration systems. Electrospinning also leaves an electrostatic charge on the nanofibers, which enhances their ability to capture aerosols, and its high porosity makes it easier to breathe while wearing an electrospun nanofiber filter.

“Electrospinning technology can facilitate the design and manufacture of masks and air filters,” said Prof. Yun Shen. “Using electrospinning technology to develop new types of masks and air filters has good filtration performance, economic feasibility and scalability. Being able to meet the demand for masks and air filters in the field is very promising.”