Coronavirus: In brighter news, sun keeps virus at bay

The first study to test the effects of sunlight on COVID-19 found it degrades in minutes when exposed to ultraviolet light.

A police officer speaks to sunbathers at Burleigh Heads on the Gold Coast. Picture: AAP.

The sea air has always been regarded as healthy but there’s a bonus for beachgoers – sunlight really could be the best disinfectant for coronavirus.

The first study to test the effects of sunlight on the virus has found that it degrades in minutes when exposed to ultraviolet light, providing more hints that socialising may be safer outdoors.

While coronavirus has been shown to survive for hours or days on surfaces indoors, 90 per cent of particles are deactivated in 10 minutes if exposed to the midday sun, according to a paper in The Journal of Infectious Diseases.

The research simulated the intensity of the sun at 40 degrees latitude, roughly equivalent to Spain, then looked at what happened to viral particles in saliva when left on surfaces. In conditions mimicking the winter solstice in Spain, when sunlight levels would be less than a UK summer, 90 per cent of particles were destroyed in less than 15 minutes. In conditions simulating high summer in Spain, the virus lasted 6.8 minutes.

The finding adds to evidence that the risks of infection are significantly reduced for people outside, where the fresh air and open spaces serve to dilute the virus rapidly.

“Our results indicate that the risk of potential exposure from contaminated surfaces may be lower outdoors,” Shanna Ratnesar-Shumate, senior principal investigator in aerobiology at the US Department of Homeland Security science and technology directorate, said. However, this is not the only factor that leads to the spread of the virus. “It’s hard to say how one of these factors, in this case sunlight, will affect overall disease transmission,” she said.

Charlotte Houldcroft, a virologist from the University of Cambridge, who was not involved in the research, said: “This is one of the reasons that outdoor activity can be more safely recommended, because surfaces you may touch while out and about in the day will be naturally UV irradiated by sunlight.”

“Surfaces touched often still need regular disinfection, but playground equipment on a sunny June day is perhaps less of a risk than it was in March. Of course, if you go to the beach and sit near members of a different household who cough, sneeze or breathe on you, the protective effects will not act fast enough to save you.”

The Times