Light as an anti-microbial agent was known for over a century. In the late 1800s, someone said that Sunlight is the best and cheapest source. In 1903, Niels Finsen was awarded the Nobel Prize in Medicine for his contribution to the treatment of infectious diseases, especially cutaneous tuberculosis, using visible light .
The short answer is the UVC can be used to disinfect surfaces, liquids & air. UVC will kill viruses and bacteria by damaging molecules like nucleic acids and proteins. UV photons between 200nm and 300nm are absorbed fairly efficiently by the nucleic acids that make up DNA and RNA, and photons below 240nm are also well absorbed by proteins.
A recent study in the US specifically done proved that High viral loads of 5 * 10^6 TCID50/ml (
Note -The TCID50 (Median Tissue Culture Infectious Dose) is just a measurement of viral titer) SARS-CoV-2 can be completely inactivated in just 9 minutes by UVC irradiation. Actually they used combined light source irradiation with UVC (254 nm) and UVA (365 nm) for this study. They also found that UVC reduced the live coronavirus by 99.7 percent in 30 seconds.
Usually UVC at 254nm is highly effective but it can be a health hazard, specially for the eyes & skin. By contrast,
far-
UVC light (207–222 nm) efficiently kills pathogens potentially without harm to exposed human tissues.
UV has been used in health establishments for quite some time for disinfection. The Chinese were the first to use UV robots to disinfect their public transport every night. Nowadays all aircraft are disinfected using UVC.
Tru-D, Xenex, UVDRobots &
Iugis are examples of just a few of the manufacturers of UV robots. There are many as the demand from healthcare establishments have gone up.
Probably sometimes home UV devices might be available. The safety of these is governed by the International Commission on Non-Ionizing Radiation Protection - and I am sure many companies must be working on these.
As for the cancer issue UVC could probably cause cancer. Experiments with mice has proven this. However, repetitive irradiation with 222nm UVC shown to be non-carcinogenic and safe for sterilizing human skin - This study has been done by the Japanese recently, (Kobe University) and this might lead to the development of a Germicidal lamp that can be safe for humans.
Other than these Photbiomodulation (PBM) using low levels of red or near-infrared (NIR) light have been used for healing wounds. Also Ultra Fast Laser Irradiation using Ultrashort pulse lasers (USPLs) emitting visible to near-infrared light have been used to inactivate a broad spectrum of viruses from HIV, human papillomavirus, encephalomyocarditis virus etc).
Hope this covers more than the answer looking for...
