Researchers from UC Santa Barbara, Oregon State University, University of Manchester and ETH Zurich are calling for a closer look at sunlight's ability to neutralize SARS-CoV-2 after finding that the most recent study on the matter was not up to par.
The team compared data from a July 2020 study that reported rapid sunlight inactivation of SARS-CoV-2 in a lab setting, with a theory of coronavirus inactivation by solar radiation that was published just a month earlier.
They noticed that the virus was inactivated as much as eight times faster in experiments than the most recent theoretical model predicted. “The theory assumes that inactivation works by having UV-B hit the RNA of the virus, damaging it,” UC Santa Barbara mechanical engineering professor and lead author Paolo Luzzatto-Fegiz said in a statement.
However, the research team felt that RNA inactivation by UV-B “might not be the whole story.” The scientists speculated that there could be another mechanism at play aside from RNA inactivation by UV-B rays such as UV-A, the less energetic component of sunlight.
“People think of UV-A as not having much of an effect, but it might be interacting with some of the molecules in the medium,” Luzzatto-Fezig explained. Those molecules in turn could be interacting with the virus, speeding up inactivation.
“So, scientists don’t yet know what’s going on,” Luzzatto-Fegiz said; “Our analysis points to the need for additional experiments to separately test the effects of specific light wavelengths and medium composition.”
If UV-A turns out to be capable of inactivating the coronavirus, this could prove very fruitful as there are now many types of inexpensive LED bulbs that are even stronger than natural sunlight. UV-A could also potentially be used to amplify the effect of air filtration systems at relatively low risk for human health.