As evident by multiple research studies and reports, when biological organisms are exposed to deep UV light in the range of 200nm to 300nm it is absorbed by DNA, RNA, and proteins.
How this affects bacteria and viruses:
- Absorption by proteins can lead to the rupture of cell walls and the death of the organism.
- Absorption by DNA or RNA (specifically by the thymine bases) is known to cause inactivation of the DNA or RNA double helix strands through the formation of thymine dimers. If enough of these dimers are created in DNA, the DNA replication process is disrupted and the cell cannot replicate.
It is widely accepted that It is not necessary to kill pathogens with UV light, but rather apply enough UV light to prevent the organism from replicating. The three main types of UV rays are UV-A, UV-B, and UV-C. Because UV-C rays have the shortest wavelength, and therefore highest energy.
UV-C has been proven to kill strands of coronavirus (below are notable research studies demonstrating the effectiveness of UV-C light on SARS and MERS).