Filtered vs. Unfiltered Far-UVC

The demand for Far-UVC products is growing, catalysed by the ongoing COVID-19 pandemic. More and more firms are taking extra steps to protect their customers and employees and reduce the spread of infection at the workplace.

Far-UVC technology is safe to use in occupied spaces, but only with the addition of a band-pass filter. This blog post aims to highlight the difference between filtered and unfiltered Far-UVC light, demonstrating that caution should be exercised when purchasing Far-UVC products.


Understanding Far-UVC


Before discussing the difference between filtered and unfiltered Far-UVC, let’s first discuss how the technology destroys pathogens safely.

For many years, UVC light has been used to kill bacteria and viruses in controlled settings. The light, which has a wavelength between 200nm and 400nm, is highly effective at destroying pathogens and works by destroying the molecular bonds within their DNA. This deactivates the pathogen so it can no longer cause harm.

UVC lamps used for sterilisation usually emit radiation at a wavelength of 254nm. Exposing humans to this wavelength is highly dangerous as it is able to penetrate our skin and eye cells, increasing our risk of developing skin cancer, burns and cataracts. Because of this, germicidal UVC must be used in controlled environments and kept away from humans.

Far-UVC light operates at a shorter wavelength than traditional UVC sterilisation products. Working between 200nm and 230nm, Far-UVC is still capable of destroying harmful pathogens, but cannot penetrate the outer layer of human skin and eye cells. This means that it is safe to use in occupied environments. It can be widely applied to a number of settings from gyms and theatres to offices, giving it a much greater potential to help in the fight against pathogens such as COVID-19.


The importance of band-pass filters


“Filtering longer ultraviolet wavelengths is critical for the human skin safety of Far-UVC devices” (Eadie et al., 2021).


On their own, Far-UVC lamps are not mono-spectral. This means that, although they emit radiation at a peak wavelength of 222nm which is safe for humans, they are capable of emitting light between 200nm and 320nm (Ushio, 2021). When unfiltered, harmful, carcinogenic radiation is emitted from the device, which has the potential to cause harm to those who are exposed to it.


A graph showing the effect of a filter on the safety of Far-UVC devices


The addition of an optical band-pass filter prevents wavelengths above the safe 230nm mark from being emitted. This is what makes Far-UVC technology safe to use in occupied environments. More information about filtered Care222® products can be found here.

Many companies are marketing their Far-UVC products as ‘safe for humans’, but not all products on the market come with a band-pass filter. Lamps that claim to operate at the safe 222nm wavelength are still capable of producing light at dangerous wavelengths, creating confusion for consumers. To ensure the safety of those who are exposed to the light, you should only purchase from trusted providers who offer filtered Far-UVC solutions.


To find out more about our Far-UVC solutions, click here.


(Image credit: Ushio)

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