In our recent post, we discussed Nebraska Medicine’s decontamination process for PPE using ultraviolet germicidal irradiation (UVGI). You may be wondering what UVGI is, and how ultraviolet lighting is able to disinfect a wide variety of materials and objects. Below we'll answer some basic questions in regards to the technology. If you would rather cut to the chase and inquire about how to obtain UV disinfection lighting for your building or facility, click here.
What is Ultraviolet Light?
Ultraviolet light is a type of naturally present electromagnetic radiation that is in sunlight and actually makes up approximately 10% of the total light generated by the sun. UV light is electromagnetic energy with wavelengths shorter than visible light but longer than x-rays. The wavelength of this light ranges from 10nm to 400nm and is classified into three sub-bands; UV-A (near), UV-B (middle), and UV-C (far).
UV light with wavelengths less than 290nm are considered to have “germicidal” properties (more on this later). Earth’s atmosphere absorbs ultramagnetic radiation with wavelengths less than 290nm, meaning that most of the UV-C and UV-B generated by the sun is blocked by our planet’s ozone.
History of UV Light Disinfection
The disinfection properties of ultraviolet lighting have been known for over 140 years, since Downes and Blunt discovered the antibacterial effects of the shorter wavelengths of sunlight. Shortly thereafter, it was proved that the UV portions of the light spectrum were able to destroy microorganisms.
After confirming UV lighting’s ability to kill pathogens, the next step was to find a way to replicate the UV wavelengths that would result in the disinfection of surfaces, air, and water. The first UV quartz lamp was invented in 1904 and resulted in the germicidal lamp. Germicidal lamps are a type of lamp that produce the wavelengths of ultraviolet light (UV-C; 200nm to 280nm) that have disinfection properties.
How does UV Light Kill Viruses and Bacteria?
Ultraviolet light kills cells by damaging their DNA. Exposure to the electromagnetic radiation (light) at certain UV wavelengths modifies the genetic material of microorganisms and destroys their ability to reproduce. The UV energy triggers the formation of specific thymine or cystosine dimers in DNA and uracil dimers in RNA, which causes the inactivation of microbes by causing mutations and/or cell death as well as failure to reproduce. (source)
According to this from the Centers for Disease Control (CDC), “UV can kill all bacteria, including drug-resistant bacteria because UV light is actually attacking the DNA and RNA of microbes. While the amount of UV needed to kill a microbe may vary as there is a relationship between the size of DNA molecules and the effect of UV radiation, there have been no reports of microbes demonstrating an ability to build an immunity to light-based methods.”
What is Ultraviolet Germicidal Irradiation (UVGI)?
UVGI is a method of disinfection that uses short wavelength ultraviolet light (UV-C) to inactivate or kill microorganisms and pathogens. Essentially, UVGI is the use of UV light with sufficiently short wavelengths to disinfect surfaces, air, and water.
The effectiveness of germicidal UV light depends on the length of time a microorganism is exposed to UV, as well as the intensity and wavelength of the UV radiation.
It is important to understand the difference between sterilization, disinfection, and decontamination as these terms are often incorrectly used interchangeably, which can cause confusion in regards to the effectiveness of UVGI (as well as the avoidance of potential legal ramifications).
- Per the CDC, sterilization describes a process that destroys or eliminates all forms of microbial life and is carried out by physical or chemical methods.
- Per the CDC, disinfection describes a process that eliminates many or all pathogenic microorganisms on inanimate objects.
- To decontaminate is to make an object or area safe by removing, neutralizing, or destroying any harmful substance.
- Basically, decontamination is the result after the processes of sterilization or disinfection.
Per the CDC, disinfection and sterilization are essential for ensuring that medical and surgical instruments do not transmit infectious pathogens to patients. Because sterilization of all patient-care items is not necessary, health-care policies must identify, primarily on the basis of the items’ intended use, whether cleaning, disinfection, or sterilization is indicated.
Are UV Lighting and UVGI the same thing?
In short, no. UVGI is a specific method of sterilization that uses UV lighting. In essence, UV lighting is a component of UVGI. UVGI is just one method of sterilization/decontamination using lighting, though, so we like to refer to is as UV disinfection lighting to encompass more than just the one UVGI method. When we say UV disinfection lighting, we mean any UV lighting that can be used in many applications to kill germs.
If you're thinking that this UV disinfection lighting technology sounds amazing and more hospitals should be using it, especially with the current coronavirus pandemic, you're right! We've known for a long time, more than 100 years, as noted above, that UV disinfection lighting kills germs. And it was popular in hospitals at one time- namely to kill tuberculosis. However, when antibiotics were first introduced, the concern for disinfecting everything lessened. Unfortunately, today there are antibiotic-resistant infections (not to mention viruses) and as a result the interest in physical decontamination has been renewed.
Additional UV Lighting Resources:
- What is UV-C Disinfection Lighting: The Basics
- Using UV Disinfection Lighting to Kill Coronavirus: FAQs, Part I
- Using UV Disinfection Lighting to Kill Coronavirus: FAQs, Part II
- Is UV Light Safe? FAQs on Safely Using Ultraviolet Disinfection
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