7 minutes is all it takes for sunlight to kill Covid-19

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Woman wearing protective mask goes through a temperature checks before going to work in the office.
Woman wearing protective mask goes through a temperature checks before going to work in the office.
Luis Alvarez / Getty Images

We can add sunshine to our list of Covid-19 preventative measures, thanks to a new study that shows sunlight can destroy the virus in under seven minutes.

The study, which was published in The Journal of Infectious Diseases, used simulated sunlight to see how effective it was in killing the virus on surfaces.

As exposure to sunlight decreased, the virus was able to survive longer.

Professor Salim Abdool Karim, the chairperson of SA’s Covid-19 ministerial advisory committee, said the study showed the importance of avoiding gatherings in enclosed spaces without sunlight as these “carry a much higher risk [of infection]”.

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He added on eNCA, however, that being out in the sun won’t prevent people from contracting the virus, but coupled with other preventative measures such as a masks, hand-sanitising and social distancing, it can reduce the likelihood of infection.

Prof Karim pointed out that restaurants in Europe, which have been allowed to reopen, have been serving customers outdoors in the summer heat. Scientists conducting the study found that “simulated sunlight rapidly inactivated SARS-CoV-2 suspended in either simulated saliva or culture media and dried on stainless steel coupons.

Ninety percent of infectious virus was inactivated every 6,8 minutes in simulated saliva and every 14,3 minutes in culture media when exposed to simulated sunlight”. The study found that “sunlight may rapidly inactivate SARS-CoV-2 on surfaces, suggesting that . . . exposure risk may vary significantly between indoor and outdoor environments”.

An earlier study published in News Medical Life Sciences had similar results.

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