In 1878, Arthur Downes and Thomas Blunt published a study highlighting the sterilization of bacteria through UV ray exposure. They realized that when the ultraviolet ray had a wavelength equal to 250 nm, the inactivation of bacteria was much more effective.
Ultraviolet sterilization is a method of sterilization that uses very short wavelengths that are part of the UVC ray category. It acts on the sensitivity of microorganisms present in all environments, thanks to its properties:
UV rays can be used to disinfect the air through longer exposure. Because the process depends on the intensity of the UV rays and on the duration of exposure, it is important to use devices in combination with ventilators so as to move the ambient air and ensure that the whole room passes through the field of UV rays.
Some systems are sometimes even installed directly in the ventilation system to maximize the results of UVC exposure to circulating air. The combination of the two therefore enables the eradication of all viruses and bacteria present in the room.
For water sterilization, a portable device powered by a low-pressure, mercury vapour battery is used. UV rays, and especially UVCs, are capable of inactivating all of the parasites that are often ultra-resistant to chemical disinfectants,such as cryptosporidia and gardia.
Unlike in air disinfection, the use of UV rays in water does not completely destroy microorganisms, as they do not dissolve them until the cells completely disappear. However, this does not detract from their effectiveness and provides a high quality of water disinfection by causing the death of microorganisms.
Sterilization of surfaces
Like all other uses, surface decontamination is done without chemicals. Not only is it better for the environment but it is also crucial in many industries.
UV rays are particularly bactericidal, virucidal and antimicrobial on surfaces, and are notably used in:
- Agri-food to sterilize work surfaces and food products;
- Supplies and professional equipment;
- Freight transport and public transport, etc.
Seldom communicated yet widely used, UV rays are common in the agri-food sector. They lengthen the shelf life of food and different food liquids.
As a result, they are free of any risk of bacteria spreading and food poisoning caused by using food products past their consumption date.
Use in the medical and surgical fields
For many years now, UV rays have been widely used in laboratories to disinfect professional instruments and equipment.
To ensure the safety of medical and surgical procedures, instruments are usually sterile. It is thanks to the bactericidal, virucidal and fungicidal properties of UV rays that medical facilities can guarantee their health safety and thus prevent the transmission of pathogenic bacteria and germs between patients and staff.
Use in spacecraft
To prevent any spread due to biological materials from Earth, international rules are very strict. Indeed, they require that all components of instruments used in space be completely devoid of pathogenic microorganisms in order to limit the spread of viruses and bacteria outside of Earth.
To do this, several techniques are implemented:
- Heating to a minimum of 120°C;
- Chemical sterilization;
- Ultraviolet oxidation;