Ultraviolet (UV) light disinfection was discovered in 1801 and UV germicidal irradiation was used for disinfection in 1910. While these disinfection methods have been used for centuries, the COVID-19 pandemic has sparked a broader interest in eliminating pathogens of all kinds among all types of businesses. As a result, many organizations have created new or improved mandates to eliminate viruses and bacteria from their offices, hospitals, hotels, schools, and other spaces where people interact.
One of the best ways to remove germs from these places is using UV-C disinfection robots. This method is not only practical but also cost-effective for continuous disinfection of almost any space. This article discusses UV-C disinfection in greater detail to help you determine your ideal disinfection protocol and supplement your current cleaning routine with ultraviolet irradiation. Read on for more information about the effectiveness of this innovative method that’s redefining the landscape of disinfection.
What is UV Disinfection?
UV disinfection is a method of killing germs that utilizes UV light-emitting devices. The devices release UV light, electromagnetic radiation that sits between visible light and X-rays depending on the wavelength. With a wavelength ranging between 10nm and 400nm, UV light exists in three types: UV-A, UV-B, and UV-C. Of these, UV-A has the longest wavelength, UV-B the next shortest wavelength, and UV-C the shortest wavelength. UV-C wavelengths have the most energy and are the most effective among the three for disinfection.
How Does UV-C Disinfection Work?
UV light disinfection works by using a device that can either be handheld, mobile, or standalone. The UV-C disinfection device emits UV-C light, which targets the microorganisms, destroying their DNA. That’s because, when exposed to electromagnetic radiation within a particular wavelength, the genetic material of the microorganisms is modified. This limits the ability of the microorganisms to reproduce, preventing their spread on surfaces within a space.
A UV-C disinfection device targets DNA to cause thymine or cytosine dimer formation. It also goes after RNA to trigger uracil dimer formation. Thymine, cytosine, and uracil inactivate the microbes, causing mutation, failure to reproduce, and eventual death. A study funded by The Centers for Disease Control and Prevention (CDC) shows that UV-C disinfection devices can enhance hospital disinfection by effectively eradicating MRSA, VRE, Acinetobacter, and C. difficile under experimental conditions.
According to recent research, SARS-CoV-2 (COVID-19) is highly susceptible to irradiation with ultraviolet light. High viral loads of 5 * 106 TCID50/ml SARS-CoV-2 can be inactivated in 9 minutes by UVC irradiation proving that UV-C irradiation represents a suitable disinfection method for SARS-CoV-2.
How Effective is UV-C Disinfection?
Because viruses contain RNA or DNA and are thus susceptible to irradiation, UV disinfection has been proven effective against a broad spectrum of microorganisms. Spores are susceptible to UV and bacteria and fungi, which both contain DNA, are similarly vulnerable to UV light.
With the longstanding use of UV for disinfection, there is a plethora of information regarding dosages necessary to inactivate different microorganisms.
The UV dose required for inactivation is the product of UV intensity [I] (expressed as energy per unit surface area) and exposure time [T]. Therefore: DOSE = I x T
This dose is commonly expressed as millijoule per square centimeter (mJ/cm2).
The reduction of micro-organisms is classified using a logarithmic scale. A single log reduction is a 90% reduction of organisms. A Log2 reduction is a 99% reduction of organisms, followed by a Log3 reduction (99.9%), etc. For example, independent testing shows that OhmniClean™ 254nm UV-C solution rapidly eliminates pathogens like MRSA, VRE, P. aeruginosa, E. coli and SARS-COV-2 with an efficacy of 99.999%.
It’s interesting to note that the degree of inactivation by ultraviolet radiation follows the Inverse Square Rule which holds that a surface that is 2x as far from the light source requires 4x the exposure to have the same effect. A surface 3x farther away requires 9X exposure.
