Why does the UV sterilization process ensure sterilization dose rather than sterilization rate?

The 253.7 nm (254 nm) light emitted by the ultraviolet Germicidal lamp coincides with the absorption spectrum of nucleic acid in microbial cells, thus destroying the molecular structure of DNA (DNA) or RNA (ribonucleic acid) in the cells of microbial organism, causing growth cell death and/or regenerative cell death, achieving the effect of sterilization and disinfection.

The effectiveness of ultraviolet sterilization is influenced by the dosage of ultraviolet radiation, rather than simply measured by the sterilization rate. Sterilization dose refers to the total amount of ultraviolet radiation received by bacteria or microorganisms, which is calculated by the product of ultraviolet Radiant intensity and exposure time. When using ultraviolet ray for sterilization, it is necessary to ensure the Radiant intensity and radiation time of the Germicidal lamp to ensure the sterilization dose. Although bactericidal dosage can be used to measure the effectiveness of killing microorganisms, it cannot directly reflect the bactericidal rate.

The sensitivity of different kinds of microorganisms to ultraviolet radiation is different, and the required ultraviolet Radiation exposure varies according to the type of microorganisms. For example, the 99.99% bactericidal rate of Escherichia coli requires a UV dose of ≥ 20000 μ W. S/cm ² (excerpted from GB15981 standard), while the sterilization rate of 99.9% for cladosporium requires a UV dose of ≥ 100000 μ W. S/cm ² (Excerpted from GB15981 standard). However, in real production, the sterilization rate is influenced by various factors, such as the shape of the irradiated object, irradiation height, irradiation time, and light intensity. In this way, we need to work together through scientific selection methods and optical simulations to obtain accurate data.