Ultraviolet Germicidal Irradiation (UVGI)
What is UVGI?
Ultraviolet Germicidal Irradiation (UVGI) is a sterilisation method which uses Ultraviolet as a method to sterilise equipment that is used for surgery. It utilises UV’s short wavelength to destroy the nucleic acids in viruses and bacteria to break down its DNA. This stops the cells from reproducing.
This method of sterilisation is also used in air systems, and when combined with filters can fully remove harmful micro-organisms from the air. UVGI is the most effective method of sterilisation we have at the moment as it has the potential to remove all microorganisms when used correctly. UV light can also be used in some cases of extreme psoriasis to help sterilise the skin. [UV2][UV3]
Image showing how UV light affects DNA structure. Source (biotecnika.org)
This is an image of a UV sterilisation machine. Image Source (Autoclave.com)
How UVGI works?
UV light can be separated into various shorter ranges such as UVA, UVB and UVC among others. UVGI uses UVC light which is on the shorter end of the spectrum. At these wavelengths, UV light can break molecular bonds within micro-organismal DNA producing Thymine dimers (Thymine is represented by 'T' in the image below). This damage to the microorganism eliminates their ability to reproduce or removes their ability to cause harm as it interferes with the organism’s DNA. A similar process occurs for humans and results in tanning or sunburn with overexposure. Fortunately we have much better natural protection from UV light and our bodies can repair small amounts of damage. [UV2][UV3]
Safety
UVGI systems use UVC, which can be harmful to humans by causing large amounts of damage to the retina of the eye, resulting in temporary or permanent vision problems. Longer exposure can causing burning (sunburn) by damaging your body’s cells through a similar mechanism by which microorganisms are destroyed.
To minimise the potential exposure to people operating the machines, they are well shielded which means the UV light cannot reach them. There are no risks from using the sterilised equipment exposed to the UV light, although plastics can have some bonds broken down which can lead to them ageing more quickly. If UV is used for skin treatment there is a small risk as there would be from using a sunbed, although the benefits of the treatment usually outweigh the risk due to UV exposure, as the dose is minimal and spread out over a course of treatments.