• Emre Cetin

Does UV Light Really Kill Coronavirus?


Ultraviolet (UV) sterilization is the most effective inactivation method against Covid-19. (perhaps the only method is known and proven) However, only one type of UV can destroy this virus: UVC. A question is posed to Dan Arnold who works at UV Light Tech Company as sales and marketing manager "why don't we put UV lights at the entrances of markets or offices and we don't sterilize people?". He answered, "you would literally be frying people".


Covid-19 epidemic (The most important agenda of the world in the first half of 2020) has not been resolved yet and remains a global epidemic. Since the epidemic news began to spread, much different protection and preservation methods have been put forward, researches and methods have been developed. But none of the methods developed haven’t helped to destroy the virus. They only work on protecting healthy people and trying to prevent the spreading virus from the infected people. Only one idea was able to cope with the virüs: sterilization with ultraviolet rays. After rumors spread about this news, lots of posts start circulating on social media titled "Coronavirus hates sunlight".

Many small or large-scale lighting and light source manufacturers which want to turn this situation of the pandemic to an opportunity, have started to launch UV Sterilization products. Moreover, they have ensured that the infollution spreading from social media has grown and provided on an academic basis. So, will the sunlight really kill the coronavirus? The shortest answer to this question is No!


Ultraviolet (UV) is a wave type in its simplest terms, just like the light. It is a form of electromagnetic radiation that is shorter than visible light and longer than X-rays. Ultraviolet radiation is found in the sun and is transported to the earth with sunlight. There are three types of ultraviolet rays from the sun. UVA (Ultraviolet A) constitutes the great majority of Ultraviolets coming on Earth, this is UV that penetrates deep into the skin and causes skin blemishes. There is also UVB (Ultraviolet B); It is the type of UV that can damage skin DNA and cause skin cancers. These two types of UV can be prevented by using a quality sunblocker.


The third and lesser-known type of UV rays is UVC (Ultraviolet C). Its wavelength is shorter than UVA and UVB and it is highly capable of destroying genetic infrastructure. According to the researches and assumptions, you can get the sunburn that you will get from UVB hours later with UVC in seconds. The good news is that we're not likely to encounter UVC from the sun right now. The great majority of UVC reaching the world is being repelled from the ozone - Fortunately, the mother nature made provision for UVC millions of years ago.

UVC sterilization is not a foreign subject. In fact, with the UVC waves obtained artificially since the first UV sterilization finding in 1878, sterilization processes are carried out quickly in hospitals, factories, and even aircraft. In addition, this method is used in the sterilization of drinking water. In drinking water cleaning processes, parasites can withstand chemicals such as chlorine. Despite this, sterilization processes are completed by using UVC; UVC's destructive powers are used against the parasite danger.


There is no (fully completed) research on the destructive effect of UVC on the coronavirus yet. However, scientists have consensus that it can at least be effective against other coronaviruses, like Sars. The issue in this consensus is the amount of UVC needed to remove the virus from the surfaces. Because, the shape of the surface, the material, and existence time affect the amount of required UVC. Unfortunately, any mathematical formula has not been found yet.


Despite, in China, public transportation vehicles have already started to be cleaned with UVC. UVC is using int the internal cleaning of the hospitals, bankers are cleaning money with UVC, and various UVC sterilization protocols have already started to be created for common indoor areas such as malls or restaurants. In addition, it should not be difficult to guess that the companies selling UV light have also broken sales records.

The World Health Organization (WHO) warns people who using UVC as a sterilization tool. It underlines the need for expert equipment and detailed training to use UVC. However, even some important politicians do not refrain from making statements that support UV sterilization. A president (you can guess who is him) suggested to administ an inner UV Light to virus-infected patients during his daily regular press conference. He did not explain what type of UV he was talking about, but when we consider the deformation that UVA, UVB, or UVC may cause on a cellular scale and consider Covid-19 infect directly lungs, we can only accept this idea as "absurd".


Recently, scientists have discovered a new type of UVC. This wave, called Far-UVC, is less harmful than normal UVC. According to uncertain results in research conducted in a laboratory environment, it does not cause DNA corruption in human skin cells. But the research process of Far-UVC is still in its infancy. Detailed reports have not been published yet. It means, commercially available UVC lamps still use Normal UVC (or Near-UVC).


There is also the subject of sunlight. The World Health Organization (WHO) says and recommends that UVA and UVB are generally effective methods of sterilization. It is known that UVA waves that interact with water in particular form hydrogen peroxide derivatives, which are the main components of many domestic disinfectant products that can kill pathogens. For viruses which suspended in midair, this process is both different and longer. However, it is also a known fact that virus-based diseases such as influenza are less common during the seasons with heavy sunlight. Scientists have monitored in a study in Brazil that flu cases also increased during periods of increased smoke density in the atmosphere due to forest fires.

Consequently, the exact results are not known about how much time the Covid-19 needs for the lethal effect of sunlight and the amount required. Even if there are some findings, the amount of UVA and UVB in sunlight varies depending on the time of day, weather, seasons, and the location on Earth. Unfortunately, artificial UVC is dangerous to use on humans and might result in deathly. Anyway, after the virus infects the human body, any UV will have no effect.


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