UV Dose and Microbial Response
UVGI inactivates microorganisms by damaging the structure of nucleic acids and proteins at the molecular level, making them incapable of reproducing. The most important of these is DNA, which is responsible for cell replication (Harm 1980). The nucleotide bases (pyrimidine derivatives thymine and cytosine, and purine derivatives guanine and adenine) absorb most of the UV energy responsible for cell inactivation. Absorbed UV photons can damage DNA in a variety of ways, but the most significant damage event is the creation of pyrimidine dimers, where two adjacent thymine or cytosine bases bond with each other, instead of across the double helix as usual (Diffey 1991).
In general, the DNA molecule with pyrimidine dimers is unable to function properly, resulting in the organism’s inability to replicate or even its death. An organism that cannot reproduce is no longer capable of causing disease.
UVGI effectiveness depends primarily on the UV dose (DUV , μJ/cm2) delivered to the microorganisms:
DUV = It
There is no known virus or microorganism that is not irradiated by UV-C at 253.7 nm this includes CoVid-19. ( SARS-CoV-2 ).
UV-C has tested effective against SARS coronovirus, (MHV ) Murine and ( CCV) coronaviridea with doses ( DuV = It ) ranging from 4 μJ/cm2 to irradiate SARS-cov P9 to 70 μJ/cm2 for Murine.
Although not actually tested and documented on Coronovirus ( SARS-CoV-2 ) there is NO CORNOVIRUS which can withstand UV-C irradiation.