At the end of February, I went on a quest for answers if it was possible to use light in the UVR spectrum  to contain and/or kill the spread of the new virus SARS-CoV-2.
The reason for validating my claim was because there are various articles, reports and white-papers available on-line prove that light in the UVC spectrum has a germicidal effect killing pathogens like bacteria, viruses, several protozoa and fungi, after exposing them 15-30 minutes to UVC light, depending their output strength. I wanted to know if this could be a possible help (as buffer) to people with a weakened immune system.
UVC is a solution in use for many years..
Most hospitals use UVC light (200-280nm) to sterilize their equipment in a short period of time. The anti-pathogenic effects of Ozone (produced with 185nm) have been substantiated for several decades, disinfecting municipal water supplies in cities worldwide. Ozone can get at places where the radiation of the UVC light cannot reach, where the light is blocked, making it more efficient against bacteria and viruses. Ozone does however not remove particles like dust and pollen from the air.
I used UVA (365nm) and UVC (280nm) light in my past apartment to effectively contain the spread of fungi. That solution has kept my bathroom and kitchen mold-free for many years.
How to use the UV spectrum without being harmful?
The most common used light in the UVC spectrum are black-lights (short UV wavelength of 254nm) which can harm the skin and eyes leading to cancers and cataracts. However it is proven that far-UVC light (207–222 nm) does efficiently inactivate bacteria and viruses because they are of micrometer or smaller dimensions, without causing harm to exposed mammalian skin. [5a and 5b]
What’s the impact of far-UVC light (and O3) on SARS-CoV
There are scientific articles on-line that 15 minutes of UVA radiation had no impact to the older Corona virus SARS-CoV, but exposure to UVC radiation did.  There are also various sources on-line, not been peer reviewed yet, claiming that UVC radiation and O3 can kill the sars-CoV-2 virus effectively. [7a and 7b]
Practical solution: sterilize the portal to inside.
I have now installed an UVC lamp (280nm) which creates O3 (185nm) in my hallway which gets only activated for 15 minutes (30 watts) when I enter the apartment from the street and when there is no movement detected for 5 minutes. It will automatically shut down on movement near/at the hallway and can only activate when enough airflow is present to get rid of the generated O3. 
How to get answers about this matter?
I did not get a lot of reactions from our peers like doctors, virologists and other scientists in microbiology, so I relaunched the question in various groups on-line to find an indefinite answer if this virus can be killed by UV radiation.
Till now, i have received interesting answers from mainly students in microbiology, that i came to the current conclusion that installing an UVC light at a portal will indeed help to kill and slow down the spread of the new sars-CoV-2 virus.
This could create an additional protection for people with weakened immunity, by offering them a buffer (in their portal) between outside and inside. I’ve already created a practical (prototype) solution in my house.
Current questions to virologists and microbiologists.
Is there anyone in the fields of virology or microbiology who can give me more insight in my claim and answer me following questions?
- Is O3 required or recommended to kill sars-CoV-2?
- Which wavelength is most efficient against sars-CoV-2?\
- Does my practical solution work to minimize contact with sars-CoV-2?
- Would this be a good buffer for people with a lowered immune system?
Thank you in advance!
With friendly regards, Gunther.
References and more information:
-  https://en.m.wikipedia.org/wiki/Ultraviolet#Subtypes
-  https://en.m.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation
-  https://scholar.google.be/scholar?hl=en&as_sdt=0%2C5&as_vis=1&q=antipathogenic+effects+of+ozone
-  https://en.m.wikipedia.org/wiki/Water_purification
- [5a] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5552051/
- [5b] https://www.nature.com/articles/s41598-018-21058-w
-  https://www.sciencedirect.com/science/article/pii/S016609340400179X
- [7a] https://www.google.com/search?q=does+o3+kill+covid19
- [7b] https://www.google.com/search?q=does+UVC+kill+covid19
-  https://autiboi.be/2020/03/29/does-far-uvc-light-and-o3-kill-sars-cov-2/ by Gunther (GV), Belgium.