The laboratory testing performed by Intertek (see results here) could not use actual SARS-CoV-2 virus that causes COVID-19 for obvious safety reasons, so the independent certified testing laboratory’s approved procedure is to use a similar and actually harder to remove virus, in this case they used Phi X174 bacteriophage. This surrogate works because it is one of the smallest known viruses (25 nm) and is a nonenveloped virus, making it resistant to UV light. The SARS-CoV-2 is larger (125 nm) and enveloped, making it more susceptible to UV light. For more details on the use of this virus as a substitute for COVID-19, search “Phi X174 bacteriophage.”
The American Journal of Infection Control has published an article located at https://www.ajicjournal.org/article/S0196-6553(20)30756-2/fulltext that specifically discusses the susceptibility of SARS-CoV-2 to irradiation with ultraviolet light. The opening section of this Journal Article includes three highlights, namely;
“SARS-CoV-2 is highly susceptible to irradiation with ultraviolet light,
High viral loads of 5 * 106 TCID50/ml SARS-CoV-2 can be inactivated in 9 minutes by UVC irradiation.
UVC irradiation represents a suitable disinfection method for SARS-CoV-2.”