Dangerous airborne viruses are rendered harmless on-the-fly when exposed to energetic, charged fragments of air molecules, a study of the University of Michigan (UM) posted on its website on Monday shows.
UM researchers have measured the virus-killing speed and effectiveness of nonthermal plasmas, the ionized or charged particles that form around electrical discharges such as sparks.
To gauge non-thermal plasmas' effectiveness, the researchers pumped a model virus into flowing air as it entered a reactor. Inside the reactor, borosilicate glass beads are packed into a cylindrical shape, or bed. The viruses in the air flow through the spaces between the beads, and that's where they are inactivated.
"In those void spaces, you're initiating sparks," said Herek Clack, UM research associate professor of civil and environmental engineering. "By passing through the packed bed, pathogens in the air stream are oxidized by unstable atoms called radicals. What's left is a virus that has diminished ability to infect cells."
During these tests, the researchers also tracked the amount of viral genome that was present in the air. In this way, they were able to determine that more than 99 percent of the air sterilizing effect was due to inactivating the virus that was present, with the remainder of the effect due to filtering the virus from the air stream.
"The results tell us that non-thermal plasma treatment is very effective at inactivating airborne viruses," said Krista Wigginton, assistant professor of civil and environmental engineering at UM. "There are limited technologies for air disinfection, so this is an important finding."
This parallel approach of combining filtration and inactivation of airborne pathogens may prove a more efficient way of providing sterile air than technologies used today, such as filtration and ultraviolet light.
Ultraviolet irradiation can't sterilize as quickly, as thoroughly or as compactly as non-thermal plasma.
The study and its results have been published in the Journal of Physics D: Applied Physics.