How Effective is UV Light in Killing Germs?

The antibacterial effects of the sun were discovered over 140 years ago. These effects are more effective in eliminating bacteria at shorter wavelengths. More discoveries show that UVC, UVA, UVB, and violet-blue light have germicidal effects where new approaches have made it possible with brands like R-Zero harnessing this ability to develop UV sanitation light systems.

How UV light kills germs

UVC, UVA, and UVB rays have different wavelengths and energy. For one, UVC is the shortest of the three at 200-400 nanometers (nm) hence it has the highest energy for killing pathogens. The energy from UV light is electromagnetic which acts by targeting these microbes to decontaminate and destroy the molecular bonds of the germs, bacteria, and viruses. Additionally, UVC disinfection kills those microbes that have developed resistance to chemical disinfectants. This UV-C energy is also used in hospitals and other health facilities to decontaminate surgical tools.  Unlike traditional methods, UVC decontaminates all surfaces the light touches including the hidden and hard-to-reach corners, crannies, and nooks. Studies show that a combo of UVC technology and traditional methods of decontamination reduced the transmission of antibiotic – resistance bacteria by 30 {496112f4e2fea7f3f9cbf1b3b8ca5c6f3a45951b4a79953f4f9c2516cb7e881b}.


The downside of using UVC is that it can be a health hazard at a broad spectrum and can lead to chronic diseases such as cataracts and skin cancer. This means, when the UVC system is running and decontaminating surfaces, humans should not at any point come into contact with the light. The good news is that there is research underway that aims at narrowing the rays’ spectrum by half.  The new spectrum will still be effective in killing germs but will not penetrate the human skin.


How effective this research is can be ascertained from a study done back in 2017 where at 222nm, UVC light eliminated germs, viruses, and the methicillin-resistance bacteria with the same intensity as would 254nm UVC light.  Since then, more tests have been done to verify the effectiveness of the narrower spectrum. These results of a non-toxic spectrum could aid much in reducing fatal viruses like the current Covid-19 and the transmission of other diseases when UVC systems are installed in public places. Additionally, UVC light will still be effective in destroying both drug-resistant viruses and newly-emerging strains lowering the need to develop toxic chemical treatments.

Violet-Blue Light

For violet-blue light, its wavelength is 405-470 nm which is highly effective in the suppression of bacteria when used at the right intervals. Through the blue light, photoexcitation of endogenous porphyrins occurs leading to the production of oxygen reactive species which are known to be toxic to bacteria. Combining violet-blue light and other wavelengths maximizes the elimination of germs. Even then, each UV light unit comes with its set of instructions on how to use, the intervals, and the distance it should be from the target area or object.

UVC light kills and destroys germs and helps prevent their reproduction. Also, at a narrow spectrum, UVC units can be used for daily needs in public areas without causing any harm to the human skin.