What is UV Light Sanitation and How Does it Work?

Since the beginning of the Coronavirus pandemic people have looked for new and better ways to disinfect their homes, venues, school and workplaces.   Special cleaning agents have been formulated and everyone is now checking the alcohol level in their products  (go for 65% and over, BTW).

With this, new interest has been taken in old technology— UVC or UV-C light irradiation.   Wands, lamps, cabinets and other UVC products seem to be everywhere.   This is a quick synopsis of what UVC light is, how it works, and what products might work for you.

Discovered in the early 1800s, UVC is one of three ranges of UV light, as determined by wavelength.  There is UVA (400-315nm) light which is commonly used in black-lights,  UVB light (315-280nm), which gives us sunburns, and at wavelength 280-100, we find UVC light.

In nature, UVC light is created by the sun but unlike the other two UV wavelengths, it is absorbed entirely by our ozone layer, never reaching the earth’s surface.   If you are old enough to recall our concerns about the deteriorating ozone layer a few decades ago, potentially dangerous UVC rays shining down on us was the reason why.  Life on earth has never had to adjust or adapt to these rays which is why they can be both dangerous to us and extremely effective bacteria and virus killers.

UVC light attacks microorganisms at the RNA level,  targeting and then killing the genetic material within.  Although not yet clinically proven against COVID 19, we do know UVC kills Streptococcus,  Influenza, Sars, and other coronaviruses, taking mites, bacteria, and some fungi out right along with them. When used correctly, UVC light is known to be 85 to 90 percent effective.

Although little known to the average consumer before the pandemic, healthcare facilities have been disinfecting with UVC for decades.  Water and air purification through UVC light is already popular in industry and home use in those areas is growing.  Today’s renewed interest in this technology is in its potential as a surface cleaner.

Fast, clean with no need for hand scrubbing or harsh chemicals,  UVC irradiation can be used as a “green” surface sterilizer with no messy residue or rags and chemicals to dispose of afterwards, UVC light is another powerful weapon in our battle against virus’s and bacteria.  But because direct exposure to UVC burns skin and eyes, (the longer the exposure, the higher the damage) it must be handled properly.   Indeed humans, animals and plants should be removed from any space as it is being UVC disinfected.  One other note of caution:  because man made UV lightwaves are identical to those of the sun, it can fade fabric colors over time. Some materials break down from UV exposure in a process called photo-degradation.

When used correctly,  UVC will work on any surface it hits as long as it is the proper wavelength: specifically 254 nanometers (nm).  The time in which it takes to disinfect a surface depends on the throw of the UVC unit and its proximity to a surface.


Of course, most spaces contain furniture, barriers, and other assorted “stuff” and this can limit the ability of UVC to thoroughly clean in one swoop.  The UVC light must directly shine on a surface in order to sterilize it.  Most lights can be more effectively used if moved around a space to get to all surfaces or they can be installed overhead. There is, however, another element that can assist  UVC light during sterilization, and that element is called Ozone.  Unless the glass UVC unit is specially coated, quartz and “soft” glasses allow 185nm to pass out into the air along with the UVC 254 rays and this wavelength produces Ozone.  A powerful disinfecting agent in and of itself, ozone can move around objects like furniture and clothing, etc.,  disinfecting surfaces UVC cannot reach. Unfortunately,  like UVC light, Ozone comes with a hitch: it’s ability to harm humans in close proximity.  In this case, breathing Ozone can harm the lungs and it is considered especially potentially dangerous to those with respiratory diseases.  While humans can reenter a room minutes after using a non-ozone producing UVC unit, they must wait for ozone to clear a room before entering.  This is why most ozone producing UVC  sanitation is done after hours, with extra time reserved to allow the Ozone to naturally dissipate. For this reason, many experts caution against the home use of Ozone products.

If the risks involved with the above concern you, there is good news:  a promising new form of disinfecting UV light that is slowly entering the market.  This exciting new UV product is called Far UVC Light.  Without getting too technical with the language (I am not a scientist after all) Far UCV emits UV at a further reduced wavelength  (207-222nm), and new studies have shown Far UV light to be effective virus and bacteria killer that does not harm humans or other mammals!   Given the current positive news on its safety and effectiveness, we should expect to see more Far UVC products in the marketplace soon.

With so many UVC surface and air cleaning products on the market it, can be hard to choose the ones that are best for you.   Rolling or stationary disinfecting lights are great for overall surface disinfecting and are portable enough to move from room to room.  Depending on the size of the space involved and the power of the unit, UCV surface disinfection typically takes 30 minutes to an hour to work.  UVC stationary or rolling units should be equipped with timers or with remote controls to give the user time to vacate the area prior to use. Overhead hard-wired units are a terrific fit for highly trafficked offices, health care facilities, and industrial buildings.  All overhead units should be installed with a motion sensor that automatically shuts off the unit if a visitor enters unawares.   UVC Cabinets and UVC boxes are recommended for high touch objects: everything from electronics to sporting equipment, tools, and small objects can be cleaned very quickly, in some cases, mere minutes due to the close proximity of the light to the objects in an enclosed space.  They are also safe for humans as quality units only work when closed and they are often equipped with timers for industries, schools, colleges, and other institutions with high volumes of items that need to be cleaned quickly and rotated out.

UVC products are worth the investment to help you as you disinfect your facilities, office, or venue spaces’ air, water and surfaces.  As with any other product, buyers should make sure their choices come from reliable and proven sources.  Unfortunately, many of the inexpensive consumer-level products flooding the market may be giving people a false— and in this case dangerous—sense of security.  Several commonly known LED wands have been tested only to find they were not powerful enough to do much of anything.   Ask your UVC provider for their certification information before buying.

Also keep in mind that no product is a magic bullet when it comes to protecting your employees, customers, and pupils from disease.   Social distancing, hand washing, and standard disinfection techniques should be used along with your UVC lighting solutions to keep us all safe where we meet.


References and Links:

Welch D.  Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases.  Scientific Reports  2018


Kalter, L.    Coronavirus Puts UV in the Disinfectant Spotlight.  WebMD  2020


Rammelsberg A.   How does ultraviolet light kill cells?  Scientific American  1998


Coffey D.  Does UV light kill the new coronavirus?  LiveScience   2020


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