Sunlight kills the coronavirus faster than expected. What’s behind it?
The coronavirus has been with us for over a year. Even today, however, we do not know how sunlight affects it, to what extent it can help curb it.
The coronavirus has enemies. They are white blood cells of a group of lymphocytes that destroy infected cells, vaccines or the sun and therefore sunlight.
Experts from the University of California, Santa Barbara, led by Professor Paolo Luzzatto-Fegiz, point to the role of sunlight. They published an article on the university’s website in which they pointed out the need to test the ability of solar radiation (more precisely the sun’s ultraviolet radiation) to destroy coronavirus particles.
The researcher found that there is an abysmal difference between theory and experimental results: the virus was destroyed in experiments with sunlight several times faster than predicted by the theoretical model.
Ten minutes is enough
In June 2020, a theoretical study concluded that 90% of coronavirus particles should be inactivated after half an hour of summer sun around noon.
One month later, laboratory researchers tested the effects of ultraviolet radiation corresponding to summer sunlight on SARS-CoV-2 in a solution similar to human saliva. In this case, the virus was destroyed in just 10 or 20 minutes.
Luzzatto-Fegiz points out that it is not clear what the difference is between the studies. No one has dealt with it yet.
“Knowing how the Sun can help us deal with coronavirus can be helpful,” the researcher wrote on the University of California website.
Who explains the difference?
The theoretical study is based on a model in which viruses destroy UVB radiation. This is ultraviolet radiation with a wavelength of 280 to 315 nanometers: one nanometer (nm) is one thousandth of a meter (10−9).
The UVB radiation band has harmful effects on living organisms. Its energy is able to break down proteins and other organic compounds.
UVB radiation also damages RNA, which carries the hereditary information of viruses. “The theory predicts that coronavirus inactivation should be much slower. The difference between experimental and theoretical results suggests that the decomposition of RNA by UVB radiation may not be the whole story,” writes Professor Luzzatto-Fegiz.
His colleague Yang-jing Chu assumes that the less energetic component of radiation with wavelengths of 315 to 400 nanometers contributes to the elimination of viruses. It is called UVA and accounts for 99 percent of the sun’s ultraviolet radiation that reaches the earth’s surface. According to Chu, it can react with some molecules, which in turn can react with virus particles and damage them.
“This difference indicates the need for new experiments to test the effects of specific wavelengths of light falling from the Sun to the Earth,” says Professor Luzzatto-Fegiz.