What is ultraviolet light?
Ultraviolet light is a type of electromagnetic radiation that is not visible to humans, but over the years has been used for different applications such as:
- Inactivation of viral pathogens
- Purification of drinking water
- Elimination of pathogens in food
Electromagnetic radiation can be classified into an ultraviolet spectrum in which we can find different categories:
- UV-A (315 to 400 nm)
- UV-B (280 to 315 nm)
- UV-C (100 to 280 nm)
The sun also produces UVC, whose wavelength ranges from 180 to 280 nm, but it does not reach the Earth’s surface, as it is completely absorbed by the ozone layer at the stratosphere level, approximately 40 km from the Earth’s surface.Ultraviolet light is a type of electromagnetic radiation that is not visible to humans, but over the years has been used for different applications such as:
- Inactivation of viral pathogens
- Purification of drinking water
- Elimination of pathogens in food
Electromagnetic radiation can be classified into an ultraviolet spectrum in which we can find different categories:
- UV-A (315 to 400 nm)
- UV-B (280 to 315 nm)
- UV-C (100 to 280 nm)
The sun also produces UVC, whose wavelength ranges from 180 to 280 nm, but it does not reach the Earth’s surface as it is completely absorbed by the ozone layer at the stratosphere level, approximately 40 km from the Earth’s surface.
What is ultraviolet light used for?
Ultraviolet light is used in different areas from water sterilization to hospitals for treatments such as wound healing. It is also used in tanning beds to maintain the consistent skin tone.
It is also used for disinfection. For example, some air purifiers use ultraviolet light to disinfect the air, eliminating pathogens that are suspended in the air. The radiation lamp is inside a chamber that does not allow UVC rays to escape, protecting the user from any danger. The light causes irreversible damage to the DNA structure, preventing it from reproducing.
Another application is for pest control, such as flies and mosquitoes, which are attracted to the lamp to be eliminated by an electric discharge.”
UV-A Ultraviolet light
UV-A ultraviolet light is found in the wavelength range of 315 to 400 nm. This type of radiation is predominant on the planet (95%), even on cloudy days, as it has the ability to penetrate clouds, glass, and even the skin.
UV-A radiation can cause different effects on the skin, such as cancer, aging, pigment disorders, allergies, among others, as well as problems in the eyes and immune system.
UV-A radiation is used in the health sector to treat some diseases, such as skin diseases like vitiligo and tumors.
Ultraviolet Light UV-B
UV-B ultraviolet light is found in the wavelength range of 280 to 315 nm. Unlike UV-A, this type of radiation only reaches the planet by 5%, as it is blocked by clouds. However, it can still penetrate the epidermis. UV-B radiation can cause skin burns, cancer, allergies, etc., although it is also known for causing tanning of the skin.
It is used in reptiles to synthesize vitamin D3, which is necessary for them, as it helps them absorb calcium from their food.
Ultraviolet Light UV-C
Ultraviolet light, specifically UV-C, is found within the wavelength range of 220nm to 290nm and is ideal for disinfecting pathogens on surfaces or in the environment. It damages the DNA of numerous microorganisms, destroying the bonds of adenine and thymine to eliminate viruses, bacteria, spores, and molds, preventing them from multiplying and causing infections.
This radiation is divided into UV-C Germicidal (254nm), which is used for disinfection in hospitals, water, or food. However, this range of light is harmful to humans and should be supervised. No people should be within the disinfection area as it can cause severe skin injuries, even blindness. There is also Far-UVC, a new radiation wavelength of 222 nm, which has the same effect as germicidal but does not penetrate the skin or eyes, meaning it does not create side effects in people. However, it is essential to know the exposure time a person can tolerate within the disinfection area.
UVC light can be successfully generated with special lamps, and its germicidal properties have been known for about 100 years. It has even been used in areas occupied by people for periods of up to 8 hours to prevent the spread of tuberculosis.
What is SARS-CoV-2?
SARS-CoV-2 is the coronavirus responsible for the current COVID-19 pandemic. It is a microorganism that contains ribonucleic acid (RNA) in its core, which is a chain with genetic information that passes from the virus to the infected cell. The virus employs the RNA of the infected cell to replicate and spread to more cells.
UV-C light against SARS-CoV-2
In a report published on April 15, 2020, the Illuminating Engineering Society of North America (IES) acknowledged that UV-C light can effectively inactivate the SARS-CoV-2 virus. The risk of developing skin cancer or cataracts from incidental exposure is considered minimal, so the operation of germicidal lamps is considered safe when used according to the instructions.
It has been shown that the 254 nm wavelength used for disinfection only has a 5 percent absorption rate in the outermost layer of the skin, compared to 15 percent for UV-A light and 50 percent for UV-B light. Even in the cornea, which is the outermost layer of the eye and more sensitive to UVC rays than the skin, only ocular irritation lasting 2 to 4 days has been observed, without any subsequent residual effects, even with exposures of 20-100 times above permissible limits. However, the use of UVC for direct disinfection of people is not recommended.
Recently, it has been reported that a UV light robot developed in Denmark has been used in Chinese hospitals, achieving a 99.9 percent removal of viruses and bacteria in the air and on surfaces.
Technological advances in this area will allow us all to adapt to the new conditions that life with SARS-CoV-2 represents until an effective vaccine or treatment is found.
