How Does Ultraviolet Light Disinfect?

Published Date: 2023-05-15 10:59:38 Views: 202

Ultraviolet (UV) light is electromagnetic radiation in wavelength bands other than visible violet light. We know that light visible to the human eye is composed of radiation with wavelengths between 380 and 740 nm. Ultraviolet light specifically refers to the part of the electromagnetic spectrum between 100 and 400 nm, which is part of invisible light.

To be clear, UV light consists of four wavelengths of rays. These are:

  • UV-A, between 315 and 400 nm, is responsible for the tanning of the skin;
  • UV-B, between 280 and 315 nm, promotes the synthesis of vitamin D and causes skin burns;
  • UV-C, between 200 and 280 nm, which disinfects and sterilizes;
  • UV-V, between 100 and 200 nm, is absorbed by water and air and exists only in a vacuum.

Both UV-B and UV-C can cause cell loss and therefore have disinfection capabilities. However, the two types of UV radiation differ greatly in the degree of damage they can cause to cells.

While the UV-C rays contained in sunlight are completely filtered out by atmospheric ozone when it hits the atmosphere, UV-B rays are able to penetrate the atmosphere and are the main harmful rays found in natural sunlight.

UV-B rays can cause damage to human cells, ranging from severe skin burns to skin cancer. It has also been found to affect the growth, development, and reproduction of many plants and animals.

Although both UV-B and UV-C are capable of damaging DNA in a similar manner, UV-B does not have the ability to effectively kill microorganisms. This is due to the fact that microorganisms are much smaller than human cells, and this requires smaller wavelengths of light to penetrate their cellular structure. Therefore, UV-C is ideal for this purpose.

When UV-C light penetrates cells, they alter the DNA of microorganisms by disrupting their DNA structure, acting as thymine dimers, which can cause serious disruptions to the processes of cell replication and protein expression that microorganisms need to survive. Scientific studies have shown that UV radiation at doses of 0.5 to 20 J/m2 can cause complete cellular collapse, leading to the death of microorganisms.

UV-C light is 99.99% lethal to bacteria and viruses and is therefore widely used to disinfect air, water, and surfaces. Specifically, UV lamps are designed to emit light at a wavelength of 254 nanometers, the most widely damaging ray found for microorganisms.

For most disinfection needs, this short-wavelength, high-energy UV light is emitted through the use of low or medium-pressure UV lamps. For routine disinfection, low-pressure lamps are ideal because they produce low-energy radiation that is energy efficient. On the other hand, medium-pressure lamps produce more energy and can damage not only the DNA of cells but also the cell walls.

Overall, UV-C is a proven effective means of disinfecting and preventing pathogenic bacteria, regardless of disinfection needs.


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