Is UVC Light Effective for Bacteria and Viruses?

Bacteria and viruses are microscopic microorganisms that can cause a variety of maladies and

conditions. To prevent the transmission of such diseases and illnesses, these microorganisms must be eliminated from surfaces and the air. Utilizing ultraviolet (UV) radiation is one effective method for achieving this. UVC light has been shown to be the most effective form of UV light for destroying bacteria and viruses. This article will explain in detail what ultraviolet C (UVC) radiation is, how it operates, and how effective it is at killing bacteria and viruses.

UVC light has a wavelength between 200 and 280 nanometers (nm). It has a shorter wavelength than visible light, as well as the UVA and UVB radiation from the sun to which we are exposed.It is also known as germicidal UV because it can eliminate the DNA of microorganisms such as viruses and bacteria.

How Does UVC Light Work?

UVC radiation functions by causing DNA damage to microorganisms such as bacteria and viruses. One of the four nucleotides that comprise DNA, thymine, forms covalent bonds with adjacent thymine molecules when exposed to UVC radiation. This results in the formation of a thymine dimer, which distorts the DNA helix structure and inhibits DNA replication. The microorganism cannot endure and reproduce without the ability to replicate.

UVC radiation must have the proper wavelength and intensity to be effective. UVC light intensity is measured in microwatts per centimeter square (W/cm2). The intensity is necessary to eradicate bacteria and viruses is dependent on the type of microorganism, the distance between the light source and the microorganism, and the duration of exposure.

UVC Radiation and Bacteria

UVC light has been demonstrated to be effective against a variety of bacterial strains. In one study, UVC light reduced the number of Staphylococcus aureus bacteria on a surface by 99.9% after just 5 seconds of exposure to 0.32 W/cm2 of UVC light. One minute of exposure to UVC light with an intensity of 1.8 W/cm2 was sufficient to eradicate 99.9% of Pseudomonas aeruginosa bacteria, according to another study.

UVC light has also been demonstrated to destroy multidrug-resistant bacteria. In one study, 10 seconds of exposure to UVC light at an intensity of 0.2 W/cm2 reduced the number of multidrug-resistant Acinetobacter baumannii bacteria on a surface by 99.9%. 5 seconds of exposure to 0.5 W/cm2 UVC light reduced the number of multidrug-resistant Klebsiella pneumoniae bacteria on a surface by 99.9%, according to a separate study.

UVC Radiation and Viruses

UVC light is found to be effective against a variety of viruses. In 15 minutes, UVC light with an intensity of 0.1 W/cm2 reduced the infectivity of the influenza A virus by 99.99%, according to one study. In another study, 15 minutes of exposure to UVC light with an intensity of 0.5 W/cm2 reduced the infectiousness of the human coronavirus OC43 by 99.9%.

It has also been shown to be efficacious against the COVID-19-causing SARS-CoV-2 virus via air disinfection. In 25 seconds, UVC light with an intensity of 0.1 W/cm2 reduced the infectiousness of the SARS-CoV-2 virus by 99.9%, according to one study. In another study, exposure to UVC light with an intensity of 0.05 W/cm2 reduced the infectiousness of the SARS-CoV-2 virus by 99.9% in just one minute.

It is essential to note that the efficacy of it in destroying viruses depends on a number of variables, including the type of virus, the intensity of the light, and the duration of exposure. However, research has demonstrated that UVC light can be a useful instrument for preventing the spread of viruses such as influenza, human coronaviruses, and SARS-CoV-2.

Restriction of UVC Light

UVC light has been demonstrated to be effective at killing microbes and viruses, but its application is limited.

● First, only microorganisms that are directly exposed to it can be killed including the UV water disinfection. Therefore, surfaces and objects not in direct contact with UVC radiation may still harbor bacteria and viruses.

● Second, direct exposure to it for an extended period of time can be detrimental to humans.Over exposure can lead to skin irritation, eye injury, and other health issues. Therefore, it is essential to adhere to UVC light safety guidelines and ensure that people are not directly exposed to the light.

● Thirdly, it is only capable of destroying bacteria and viruses if it is applied with the proper intensity and duration. It may not be effective at eradicating microorganisms if the intensity or duration of exposure is insufficient.

● Finally, UVC radiation may not be effective against all bacteria and viruses. Some microorganisms and viruses may be more resistant to UVC light than others.

Not All UV Lights are same!

Not all UV radiation is equally effective at destroying bacteria and viruses. There are a variety of UV light varieties, each with distinct wavelengths and properties. To comprehend the differences between UV light varieties, it is necessary to examine the ultraviolet spectrum.

UV-A and UV-B

UV-A and UV-B are the most well-known forms of ultraviolet light, and they are the sun's rays that reach the Earth's surface. However, other forms of UV light are commonly used in products that disinfect the air.

UV-C

UV-C, also known as germicidal UV, consists of wavelengths between 200 and 280 nanometers. This is the conventional form of germicidal UV that scientists have used for more than a century to disinfect water, air, and surfaces. UV-C effectively destroys and deactivates all types of microorganisms, including viruses, bacteria, mold, and fungi.

Far-UVC

Far-UVC is a subset of UV-C, consisting of wavelengths between 207 and 222 nanometers. Far-UVC is distinct in that it is believed to be harmless for human exposure. This particular spectrum of light has a very narrow bandwidth that prevents it from penetrating beyond the outermost layer of our epidermis, but it can still kill viruses and bacteria. In the last decade, scientists began focusing on far-UVC, so research into potential adverse effects is more limited than for UV-C.

Near UV

Near UV consists primarily of UV-A wavelengths, which still possess some germ-killing properties but cannot destroy viruses like UV-C. In medical facilities and senior care facilities, near ultraviolet light can help reduce bacterial infection rates. These wavelengths are very near to the spectrum of visible light and are thought to be safe for humans.

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