Ultraviolet Germicidal Irradiation UVGI

A Primer on UVGI (Ultraviolet Germicidal Irradiation)

What is UVGI (Ultraviolet Germicidal Irradiation)?

Ultraviolet Germicidal Irradiation (UVGI) is electromagnetic radiation that can destroy the ability of microorganisms to reproduce by causing photochemical changes in nucleic acids.  Wavelengths in the UV-C range are especially damaging to cells because they are absorbed by nucleic acids.

UV radiation affects the DNA/RNA of pathogens by breaking the Thymine bonds of the helix and cross-linking them (also known as Thymine Dimer).

The Wells Riley Equation (see below) must be calculated to determine UVGI solution effectiveness…

The terms used.

The Wells Riley Equation is used to calculate infection probabilities in an occupied space.  Probability increases as exposure time (t) increases and/or clean airflow (Q) decreases.

Wells Riley only accounts for airborne infections…. infections from close contact can be mitigated by the wearing of face masks, social distancing, and cleaning.

What you should know about UVGI and Kitchen Ventilation

  • UV-C lamps at 254nm (i.e., non-Ozone producing) can be used for supply-air systems sometimes called UVGI, UV Germicidal Irradiation.
  • UVGI (Ultraviolet Germicidal Irradiation) does not kill pathogens, it makes them inert, which is one way of reducing the chances of the pathogens mutating.
  • There is virtually no point in incorporating UVGI (UV Germicidal Irradiation) into the supply air ventilation system.  Fresh air does not convey the virus…. people do!
  • In spaces that are poorly ventilated, have recirculation as part of the space conditioning strategy, have high occupancy levels, or where people spend a lot of time in the same space…. UVGI can be utilized to sterilize the air.
  • UVGI can also be used to ensure the heating/cooling coils are not a breeding ground for bacteria, fungi, and moulds, as viruses can only multiply in a host organism.
  • UVGI (Ultraviolet Germicidal Irradiation) is not a new technology as it has been around since 1877 when it was demonstrated to disinfect water and later in the 1950s when it was used to eliminate TB from hospital exhaust air.  Standalone units are now readily available.

Should you require help in selecting a UVGI unit for your facility, the experts that manufacture these types of units can guide you on the proper selection and any accessories needed to meet your requirements.


Read another article relating to UVGI How effective is Ultraviolet Germicidal Irradiation (UVGI) lights in neutralizing a virus?(Opens in a new browser tab)


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Comments

    • Steve Brown
    • August 26, 2021
    Reply

    Are these two statements contradictory?
    • UV-C lamps at 254nm (i.e., non-Ozone producing) can be used for supply-air systems sometimes called UVGI, UV Germicidal Irradiation.
    • There is virtually no point in incorporating UVGI (UV Germicidal Irradiation) into the supply air ventilation system. Fresh air does not convey the virus…. people do!

      • Rich
      • August 26, 2021
      Reply

      Hi Steve,
      Thanks for your comment. I see your point. The use of UVGI in supply air systems can ensure the heating and cooling coils are not a breeding ground for bacteria, fungi and mould as viruses can spread in a host organism. From that perspective, they have value. Treating supply air is problematic as exposure time to UVGI is critical to the effectiveness and it has not been determined that supply air is a major contributor to virus spread, people are. Perhaps some further clarification is needed there

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