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Application of Ultraviolet Germicidal Lamps in Preventing the Spread of the Novel Coronavirus

2021-03-26

Application of Ultraviolet Germicidal Lamps in Preventing the Spread of the Novel Coronavirus

I. Concepts of Ultraviolet Lamps and Ultraviolet Radiation

Like table lamps, ceiling lights, and streetlights used for everyday illumination, ultraviolet lamps are also electrical light sources whose primary function is to emit electromagnetic radiation. The key difference between UV germicidal lamps and lamps used for everyday lighting lies in the nature of their emitted radiation: lamps for everyday lighting emit visible light with wavelengths typically ranging from 380 nm to 780 nm, whereas UV germicidal lamps emit radiation in the ultraviolet spectrum.

Ultraviolet (UV) radiation refers to electromagnetic radiation with wavelengths ranging from 100 nm to 400 nm. Among these, UV radiation with wavelengths between 315 nm and 400 nm is called UVA; UV radiation with wavelengths between 280 nm and 315 nm is called UVB; and UV radiation with wavelengths between 100 nm and 280 nm is called UVC. [1] Different wavelengths of ultraviolet radiation have different applications; among them, UVC is the UV radiation band used for sterilization and disinfection. The ultraviolet sterilization lamps commonly referred to typically refer to UV lamps with a peak emission wavelength of 253.7 nm. [2],[3] 。

 

    

Figure 1 – Distribution of Ultraviolet Radiation in Light

 

Note 1: Ultraviolet radiation with a wavelength of 185 nm has also been the subject of related research and case studies in the field of sterilization and disinfection. The ultraviolet radiation central wavelength specified by national standards for UV germicidal lamps is 253.7 nm.

Note 2: Unless otherwise specified, “ultraviolet radiation” in the following text refers specifically to “UVC ultraviolet radiation.”

 

II. Broad-spectrum bactericidal and disinfecting effects of ultraviolet radiation

Studies have shown that ultraviolet radiation kills microorganisms—such as bacteria, viruses, and spores—primarily by causing radiation damage to these pathogens and disrupting the function of their nucleic acids, thereby achieving disinfection. [4] The germicidal effect of ultraviolet radiation on bacteria and viruses has been confirmed against common bacterial and viral strains. Bacterial strains include Mycobacterium tuberculosis (Mycobacterium), Vibrio cholerae, Pseudomonas species, Salmonella species, Enterobacter species, Salmonella typhimurium, Shigella species, Staphylococcus species, Streptococcus species, and Escherichia coli. Viral strains include influenza virus, poliovirus, rotavirus, tobacco mosaic virus, and hepatitis B virus. Fungal spores include Aspergillus species, Penicillium species, toxigenic Penicillium, and other Penicillium species. Algal strains include Paramecium species, green algae, and various protozoan species. [5] Therefore, ultraviolet radiation is a broad-spectrum method for sterilization and disinfection.

 

Figure 2 – Examples of viruses that can be inactivated by ultraviolet radiation

 

III. 2019 Infection Prevention for the Novel Coronavirus

From an infectious disease perspective, the transmission of the 2019 novel coronavirus primarily occurs via respiratory droplets—this route allows the pathogen to spread from carriers to susceptible individuals and cause infection. [6] From the perspective of transmission channels, the prevention and control of infection from the 2019 novel coronavirus should be considered from the following three aspects:

  • From the perspective of the source of infection: Isolation.

  • From the perspective of transmission routes: physical protection or pathogen inactivation.

  • From the perspective of susceptible populations: Boost immunity.

     

Wearing masks and using alcohol/disinfectants/ultraviolet radiation to disinfect environments and objects are all measures aimed at cutting off transmission routes. Among these, methods such as wearing masks constitute barrier protection, while wiping with alcohol, spraying disinfectants, and using ultraviolet germicidal lamps are methods that directly kill viruses.

In terms of virus inactivation, compared to disinfection methods such as UV germicidal lamps, alcohol wiping, and spraying disinfectants:

  • Similarities: Both are broad-spectrum sterilization and disinfection methods.

  • Differences: There are differences in usage and operational convenience.

Figure 3 – Schematic Diagram of Virus Transmission Routes

 

IV. Effectiveness of Coronavirus and Ultraviolet Germicidal Lamps

There are many types of coronaviruses. The virus that causes the common cold, the SARS-CoV virus that caused the 2003 SARS outbreak, and the newly discovered 2019 novel coronavirus (2019-nCoV) all belong to the coronavirus family. The pathogenicity and clinical manifestations of different types of coronaviruses vary considerably. [7] The 2019-nCoV discovered this time is the seventh known coronavirus capable of infecting humans. [8] 。

The virus is sensitive to ultraviolet light and heat. [6] The preceding text mentioned that ultraviolet radiation exhibits broad-spectrum antiviral efficacy by disrupting nucleic acids. During the SARS outbreak in 2003, studies also confirmed the virucidal effect of ultraviolet radiation on the SARS coronavirus in vitro. [9] Therefore, as a (coronavirus), the 2019 novel coronavirus can theoretically be inactivated by ultraviolet radiation.

The dose of ultraviolet radiation capable of inactivating viruses is related to the following factors:

  • The total amount of ultraviolet radiation depends on both the duration and intensity of the radiation.

  • The external environmental conditions in which the virus exists, including ambient temperature and humidity;

  • Viruses and their attachment to extracellular surfaces, as well as the penetrability of ultraviolet radiation.

 

V. Precautions and Recommendations for the Use of Ultraviolet Radiation

While ultraviolet radiation effectively kills bacteria and viruses, it can also harm human skin and eyes. Therefore, when installing and using ultraviolet radiation, while ensuring that its radiation dose is sufficient to achieve sterilization and disinfection, it is also essential to:

Use under unmanned conditions (avoid direct exposure to the human body).

       

Based on the germicidal and disinfecting effects of ultraviolet radiation as well as its impact on the human body, the following recommendations are proposed for its installation and use:

  • Consider using ultraviolet germicidal lamps to sterilize and disinfect items that may harbor pathogens.

  • Consider using ultraviolet germicidal lamps for environmental disinfection under unmanned conditions to eliminate pathogens that may be attached to airborne particulates and the surfaces of objects.

  • Consult with a professional to obtain installation recommendations, ensuring that the spatial arrangement of the UV disinfection lamps achieves the necessary dosage for effective sterilization and disinfection.

 

VI. Summary

Ultraviolet radiation, with a center wavelength of 253.7 nm, exhibits broad-spectrum antimicrobial activity against bacteria and viruses. Its effectiveness has been experimentally verified against the SARS virus. Theoretically, based on the nucleic acid-damaging effect of ultraviolet radiation, a certain dose of UV radiation can inactivate the novel coronavirus 2019. When used in unmanned environments, UV germicidal lamps can achieve infection prevention by disrupting transmission routes through their sterilization and disinfection effects.

Due to the harmful effects of ultraviolet radiation on human health, from the perspective of the effectiveness of protective measures against the 2019 novel coronavirus, we should also take into account other practical considerations—for example, situations in which pathogens in the environment cannot be effectively eliminated by UV radiation because they are concealed or shielded. Another scenario is when multiple individuals enter an environment that has already undergone sterilization and disinfection; some individuals may carry pathogens on their bodies and thereby transmit them to others, continuously contaminating the environment. For the general public in daily life, it is also necessary to comprehensively compare the practicality of UV radiation-based sterilization and disinfection with that of other disinfection methods, such as alcohol and disinfectant solutions.

 

 

[1] IEC 60050-845 International Electrotechnical Vocabulary (IEV) – Part 845: Lighting.

[2] GB/T19258-2012 Ultraviolet Germicidal Lamps.

[3] GB 28235-2011 Safety and Hygiene Standards for Ultraviolet Air Disinfectors.

[4] Yang Huaming, Yi Bin. Modern Hospital Disinfection Science [M]. Beijing: People's Military Medical Publishing House, 2002: 55-60.

[5] Zhang Fuyun, Kuang Fan. Experimental Observation on Factors Influencing the Germicidal Effect of Ultraviolet Lamps [J]. Chinese Journal of Disinfection, 2005, 22(3): 318-319.

[6] Diagnosis and Treatment Protocol for Pneumonia Caused by Novel Coronavirus Infection (Trial Version 4).

[7] https://baike.baidu.com/item/Coronavirus/2247364?fr=aladdin.

[8] Interpretation of the Diagnosis and Treatment Protocol for Pneumonia Caused by Novel Coronavirus Infection (Trial Version 4).

[9] http://www.chinanews.com/n/2003-06-04/26/310489.html.

 

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