US government reveals details of sunlight study on virus

The US Department of Homeland Security reveals to AFP new technical details regarding its hotly anticipated study into how ultraviolet radiation destroys the new coronavirus, saying that its experiment accurately mimicked natural sunlight.

A summary of the research was presented last week at the White House, with some scientists calling for caution until a more comprehensive report is made public.

DHS official William Bryan had briefed the media that the amount of virus on a non-porous surface shrunk by half in just two minutes when sunlight was present, the temperature was 70-75 degrees Fahrenheit (21-24 Celsius) and humidity was 80 percent.

The amount of virus suspended in air shrunk to half its amount in just 1.5 minutes at room temperature and 20% humidity, he added.

These eye-catching results surprised experts because most of the UV light contained in natural sunlight belongs to a subtype called UVA, which causes human skin to tan and age but has not generally been proven harmful to viruses, David Brenner, director of the Center for Radiological Research at Columbia University Medical Center, tells AFP.

On the other hand, a part of the spectrum called UVC is particularly adept at warping the genetic material of animal and virus cells and is widely used in sterilizing lamps, but it is not present in sunlight because it is filtered out by the Earth’s atmosphere.

A DHS spokesman adds that the test — which was conducted at the National Biodefense Analysis and Countermeasures Center in Maryland — was carried out on droplets of simulated saliva on a stainless steel surface.

Brenner, who is himself performing research into another area of the UV spectrum called far-UVC, which kills microbes without penetrating human skin, says the DHS findings does not comport with previous research.

“There is a peer-reviewed paper in the literature from the FDA (Food and Drug Administration) showing the earlier SARS-CoV virus did not respond to UVA light (though it did respond to UVC light),” he says, adding it is “reasonable to assume that all coronaviruses respond roughly the same way to light.”

The results as presented were “straining credulity,” he adds.

But a DHS spokesman says that study will soon be submitted for peer review and published in scientific journals.

“While the results are still undergoing a rigorous scientific review, we felt it important to share information on the emerging trends that are being identified in our tests,” the spokesman says.

— AFP