UVC Sterilization Mechanism and Influencing Factors

Table 1. Classification of ultraviolet rays
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Table 1. Classification of ultraviolet rays
Classification Wavelength /nm
Long-wave UV（UVA） 315-400
Medium-wave UV（UVB） 280-315
Short-wave UV（UVC） 200-280
Vacuum UV（VUV） 100-200

Table 2. Elimination mechanism of UVC

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Table 2. Elimination mechanism of UVC

No.	Research subject	UV wavelength /nm	Elimination mechanism	Reference
1	Adenovirus	210-290	DNA damage at 240–290 nm is the main cause of microbial inactivation，and the presence of components other than DNA damage below 240 nm leads to microbial inactivation	［13］
2	Bacillus alicyclic acid	275	DNA damage is the main cause of microbial inactivation	［28］
3	Foodborne pathogens and yeasts	266-279	DNA damage is the main cause of microbial inactivation	［29］
4	MHV-A59 virus	254	Protein damage accounts for 12% and genomic damage accounts for 88%	［30］
5	SARS-CoV-2	253.7	Genomic damage without damaging viral proteins	［31］
6	Gram-positive and Gram-negative pathogenic bacteria	222，254	Sub-lethal damage from 254 nm low pressure mercury（LP Hg）lamp treatment is mainly due to DNA damage，while sub-lethal damage from 222 nm KrCl UV lamp treatment is due to membrane，enzyme，and DNA damage	［6］
7	Salmonella Typhimurium and Lactobacillus monocytogenes	280，222	Cell membrane damage contributes to accelerated pathogen inactivation caused by combination therapy	［32］
8	Foodborne pathogens	UVC and HClO	The mechanism of synergistic effects is related to membrane damage and，to a lesser extent，changes in membrane permeability	［33］
9	Foodborne pathogens on the surface of cheese	222	The synergistic effect of outer membrane damage and lower photo-reactivation rate may cause an enhanced dissipative effect	［10］
10	Adenovirus	200-300	Enhanced inactivation at low wavelengths correlates with adenovirus protein damage at these wavelengths	［16］
11	E. coli O157：H7	222，282，and 254	The higher elimination efficiency of 222 nm than 254 nm and 282 nm UV sources may be due to the damaged cell envelope	［34］

Table 3. Short-wave UV for medical applications

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Table 3. Short-wave UV for medical applications

No.	Medical symptom	Whether it is better than traditional medical？	Illumination time	Whether it it safe？	Ref.
1	Herpes pharyngitis in children	Yes	Illumination 8-10 s	Yes	［54］
2	Pediatric herpetic stomatitis	Yes	Once a day，4-6 s each time，for 5 d	Yes	［55］
3	Mouth ulcers after chemotherapy for childhood leukemia	Yes	First irradiation 6 s，1 time per day	Yes	［56］
4	Pediatric pneumonia	Yes	Increases with age，maximum time 5 s，	Yes	［57］
5	Oral mucositis in hematopoietic stem cell transplant patients	Yes	6 s for the first irradiation，1 s for each increment，1 time per day	Yes	［58］
6	Post-burn residual wounds	Yes	Irradiation 20-30 s	Yes	［59］
7	Radioactive oral mucositis	Yes	First treatment 1-10 s，increasing by 1 s day by day	Yes	［60］
8	Acute drug phlebitis	Yes	Irradiation for 10-20 s，1 time per day	Yes	［61］
9	Oral mucositis after chemotherapy for ovarian cancer	Yes	Illumination 5-10 s		［62］
10	Oral mucositis after hematopoietic stem cell transplantation	Yes	The first irradiation is 6 s，and each time increases by 1 s		［63］
11	Poor incision healing after cesarean section	Yes	Adjustment between 1 and 60 biological doses depending on the actual situation		［64］
12	Herpes zoster	Yes	Initial dose of 8-10 biological doses，followed by incremental increases of 20%-30%		［65］