Where does UV based technology light come from?
Sunlight consists of different kinds of ultraviolet radiation, also known as UV (Figure 1). UV based radiation is an electromagnetic radiation just outside the electromagnetic spectrum, making it invisible to the human eye. This type of radiation comes in wavelengths ranging from 100 to 400 nanometres. It is subdivided into three categories by wavelength:
- A: UV; wavelength 315 - 400 nm
- B: UV; wavelength 280 - 315 nm
- C: UV; wavelength of 100 - 280 nm
Different types of radiation have different properties, depending on their wavelength. UV-A reaches the earth’s surface, largely passes through glass and clothing and causes one’s skin to age.
UV-B is another type of radiation that reaches the Earth’s surface. You might think that B stands for ‘brown’, because it makes you tan or burn. Then there is UV , which is blocked by the atmosphere and does not reach the Earth. This is just as well, because this type of radiation has a large amount of energy and can be very harmful to humans when they are directly exposed to it.² UV based light can be generated with the help of special lamps such as LEDs and fluorescent lamps.
What is the effect of UV based light?
As wavelengths get shorter (like UV), the light contains a greater amount of energy.¹ This energy can damage the DNA and RNA of viruses and bacteria. Some UV wavelengths are better than others at inactivating viruses. For example, wavelengths in the UV range are particularly damaging to cells because they are absorbed by nucleic acids and proteins. Germ-killing effectiveness ranges from 200 nanometres to 300 nanometres, peaking at 250-265 nm. UV based light is effective against organisms because it directly attacks the DNA and RNA. Thymine, cytosine, adenine and guanine together form the basic components of DNA (see Figure 2). When DNA comes into contact with UV based light, a chemical bond is formed that causes the thymines to dimerise, which means that they grow together.
UV based light is effective against organisms because it directly attacks the DNA & RNA. Thymine, cytosine, adenine and guanine together form the basic components of DNA (see Figure 2). When DNA comes into contact with UV based light, a chemical bond is formed that causes the thymines to dimerise, which means that they grow together.
The deadly effect of UC based rays is mainly due to the structural defects they cause when thymine dimers are formed. If enough of these dimers are made in the DNA, the DNA replication process is disrupted and the cell cannot replicate.
It does not remove the cells, it kills the organisms and prevents them from reproducing. This also prevents organisms from becoming resistant to UV based light. In combination with the right factors, UV based light is very effective at killing germs, and it can achieve a high log reduction across the spectrum of pathogenic micro-organisms.
Would you like to know how UV baed light is used? Be sure to read this this article.
- Rob Reddick. (2021). Type of ultraviolet light most effective at killing coronavirus is also the safest to use around people. Retrieved from: https://theconversation.com/type-of-ultraviolet-light-most-effective-at-killing-coronavirus-is-also-the-safest-to-use-around-people-169602
- Honeywell. (2000). Tech Lit Documents. Consulted from: https://customer.honeywell.com/resources/techlit/TechLitDocuments/50-0000s/50-8788.pdf