It depends on the application. There are some good applications for UV-C and others that are better suited for Krypton™ disinfection lighting. UV-C light can effectively deactivate bacteria and viruses. However, these organisms can often repair the DNA damage caused by UV-C light if they are exposed to light that includes UV-A or visible blue wavelengths in a process called photoreactivation. Less than 10 hours of exposure to the sun or fluorescent lights can rejuvenate the majority of exposed organisms in some cases. Less than an hour can even result in unacceptable conditions. Since both sunlight and fluorescent light include UV-A, UV-C lamps are not as effective in those environments. That said, a significant amount of municipal drinking water is treated successfully with UV-C. This works well as it is typically not exposed to UV-A light after treatment and/or it is consumed shortly after it is.
UV-C is also a carcinogenic safety risk for human exposure which prevents its use in occupied spaces, but it can be effective in spaces that are unoccupied. Unfortunately, it is during occupied hours when people are breathing, talking, coughing, sneezing or touching things that the risk of disease spread is the greatest. We have heard that talking for 5 minutes is the equivalent to a sneeze. Therefore, while UV-C disinfection at night may be effective in controlling pathogens that were deposited during the day, it does nothing to reduce the spread that occurs during the day when contamination events occur.
In contrast to UV-C, Krypton disinfection lighting is not subject to photoreactivation because the organisms have been structurally destroyed and are truly dead while maintaining all the advantages of residue-less functioning and is uniquely safe for human exposure. Krypton disinfection lighting kills organisms on surfaces, but also, in the air – meaning the small particulates that hang in the air for hours as a result of respiration, coughing, etc are disinfected just as the surfaces are. Thus, Krypton disinfection lighting is best used in spaces exposed to light and/or those that are occupied.
Some have also inquired about whether upper air UV-C disinfection systems might already be effective enough. Upper-Air germicidal UV-C (254nm) systems are designed not to expose people to their harmful radiation. However, when a carrier contaminates a space either with a sneeze, cough, talking, or breathing, gravity immediately begins to pull most of the pathogens towards the ground or other surfaces (such as desks, chairs, etc). As a result, while these upper air systems may also use air handling systems to try to fight gravity, they may not address a meaningful amount of the contaminated air and surfaces and may even keep pathogens airborne longer which could create more dangerous environments. They also do not provide any surface treatment. Because Krypton lighting is safe for human exposure, it can kill from the ceiling to the floor, providing a much more comprehensive disinfection solution.
Some have wondered whether hiring someone at $15 an hour to wipe down surfaces may be more economical than using Krypton disinfection lighting. This seems highly unlikely as in 8 hours the cost of that resource (not including benefits or payroll taxes) is $120, which would imply over 45 lights would have to be installed at the daily amortized cost of ~$2.56, which is often far more space than an individual could continuously wipe down, not to mention exposure risks to both that resource and the likelihood of human error leading to more exposure for the other occupants of the space (given studies have concluded that even in operating rooms, manual cleaning can be as little as 25% effective even when the additional emphasis is focused on the task).