March 2017

The commercial success of whole-room ultraviolet disinfection devices has increased public and professional awareness of the the germicidal properties of non-visible light.

However, studies indicate visible wavelengths of light may be appreciably antimicrobial as well.

In 2006, researchers demonstrated inactivation of Staphylococcus aureus and Pseudomonas aeruginosa with 405 nm light.  In 2007, researchers used brief pulses of visible light to inactivate viruses in blood plasma.  Subsequently efficacy has been demonstrated against a host of bacteria ranging from Listeria to Shigella.  Since visible light is less toxic to human cells than UV light, it has also been evaluated for use in decontamination of blood. Photon for photon, visible light is much less antimicrobial than UV light but it has the benefit of being less deleterious to other non-target biological materials.

On March 01, 2017 the American Council on Science & Health released a report highlighting the potential for visible violet light in refrigerators to prevent the growth of foodborne pathogens including Salmonella.  

Refrigerators with UV lights were marketed after World War II but did not succeed commercially. Since visible light is less damaging to cells (causes less color and taste change in food), perhaps visible germicidal lights in refrigerators will be a success.