Germicidal efficacy of ultraviolet rays against Coronavirus and other pathogens

Numerous studies have been produced in recent decades showing that C-type ultraviolet rays are unequivocally effective in killing populations of many types of pathogens including Coronaviruses, of which SARS-CoV-2 is one, as also reported by the Regional Health Agency of Tuscany in this article.

Recent studies show that the doses of UV-C radiation required to sterilize a surface with Covid-19 at 99.9% are approximately 3.7 mJ/cm2, in agreement with values already known for other Coronavirus variants. Technical characterisations of the HELO4 sterilizer show that the UV-C dose it is able to produce on surfaces can reach up to 1710 mJ/cm2 under optimum conditions, a dose sufficient to sterilize well over 99.99% of Covid-19. This is to be considered an ideal dose as the distance from the source and the orientation of the object relative to the source affect the dose achieved. Other characterisations of the sterilizer show that in the worst conditions (except for surfaces covered by the rays) the dose reached is of the order of the 3.7 mJ/cm2 mentioned, therefore sufficient to sterilize 99.9% in the worst conditions of exposed objects at maximum distance from the source. It should be noted that for the effective sterilisation of all objects it is advisable to carry out a further sterilisation cycle exposing the faces that were not exposed in the first cycle to UV radiation.

Similar considerations can also be made for various other categories of pathogens, some of which are more or less resistant to UV-C radiation. The power of the LED has been carefully chosen to ensure both an effective sterilising effect and to avoid deterioration over time of the characteristics of the materials subjected to sterilisation.

Some references:

National Institute of Astrophysics

Bianco, A. (2020, June 5). UV-C irradiation is highly effective in inactivating and inhibiting SARS-CoV-2 replication. MedRxiv.

Duan SM, Zhao XS, Wen RF, Huang JJ, Pi GH, Zhang SX, Han J, Bi SL, Ruan L, Dong XP; SARS Research Team. Stability of SARS coronavirus in human specimens and environment and its sensitivity to heating and UV irradiation. Biomed Environ Sci. 2003 Sep;16(3):246-55. PMID: 14631830.

Heßling M, Hönes K, Vatter P, Lingenfelder C. Ultraviolet irradiation doses for coronavirus inactivation - review and analysis of coronavirus photoinactivation studies. GMS Hyg Infect Control. 2020 May 14;15:Doc08. doi: 10.3205/dgkh000343. PMID: 32547908; PMCID: PMC7273323.

Kariwa H, Fujii N, Takashima I. Inactivation of SARS coronavirus by means of povidone-iodine, physical conditions and chemical reagents. Dermatology. 2006;212 Suppl 1(Suppl 1):119-23. doi: 10.1159/000089211. PMID: 16490989; PMCID: PMC7179540.

CE compliance