Ultraviolet germicidal irradiation

Ultraviolet germicidal irradiation (UVGI) is a disinfection method that uses short-wavelength ultraviolet (called UV-C with 254nm wavelength) light to kill or inactivate microorganisms. UVGI disinfection technology is well proven and widely used since many decades in many applications such as surface disinfection, air purification, water treatment.

Ray spectrum and the germicidal range

Ultraviolet light (UV) is a form of invisible light for the human eye, transmitted in the form of waves, which are described by their wavelength and measured in nanometres (nm) and split into the following spectral range classification bands:

Optimal germicidal wavelength

The entire UV spectrum can kill or inactivate many microorganisms, but UV-C energy provides the most germicidal effect, with 254nm being the optimum wavelength to kill harmful microorganisms in the air, water and on surfaces. UV-C light with 254nm wavelength is proven to effectively deactivate SARS-COV-19 virus and other germs.

How UVGI works?

Ultraviolet radiation C (UV-C) is produced by the sun and reproduced by man-made lighting sources. UV light germicidal systems destroy, kill, or inactivate microorganisms such as viruses, bacteria, and fungi.

The DNA, RNA and proteins of microorganisms absorb the ultraviolet light. By absorbing this energy, a photochemical reaction is triggered that breaks the DNA’s chemical bonds and inactivates the bacteria, virus or fungi. As a result, the germs can no longer reproduce or grow.

Germicidal Effectiveness with UV-C Dose Control

UV Dose is the amount of UV radiation that a microbe is exposed to, and it depends on:

  • Light Intensity: The greater the intensity (Strength of UV source) the more UV energy can be delivered to the contaminant resulting in a greater disinfection or kill rate.
  • Exposure time: The greater the exposure time (Contact time between the contaminant and the UV source), the more UV energy can be delivered to the contaminant resulting in a greater disinfection or kill rate.

It is well proven that it is not necessary to kill pathogens with UV light, but rather apply enough UV light to prevent the organism from replicating. The UV doses required to prevent replication are orders of magnitude lower than required to kill, making the cost of UV treatment to prevent infection commercially viable.

Germicidal Effectiveness Levels: Reduction levels of one million bacteria on a medical device.

Safety Caution

The WHO cautions that UV lamps should not be used to sterilise hands or other areas of skin, as UV radiation can cause skin irritation. Acute (short-term) effects include redness or ulceration of the skin. At high levels of exposure, these burns can be serious. For chronic (long-term) exposures, there is also a cumulative risk, which depends on the amount of exposure during your lifetime. The long-term risk for large cumulative exposure includes premature aging of the skin and skin cancer.
ZENZOE systems are equipped with UV-C safety systems to detect the human presence and switch off the UV-C lamps automatically, as well as an emergency stop provision. However, operators shall wear suitable Personal protective equipment (PPE) while operating UV-C disinfection solutions. Please contact us to know more details.

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