UVC Lighting Ultraviolet Disinfection of Radiological Instrumentation

This unsolicited report was prepared by Washington River Protection Solutions LLC for the U.S Department of Energy by E. B Wilkes. XtraLight extrapolated data from document RPP-RPT-62241 Rev. 01 to create this blog post.  See the press release here

E. B. Wilkes, Washington River Protection Solutions LLC

September, 2020

Download the original document here:

“Ultraviolet Germicidal Irradiation (UVGI) has a definite future in the control of contagious diseases, and if applied on a widespread basis, it may be the key to controlling epidemics and pandemics. No other current technology has the capability, the adaptability, and the favorable economics to make it viable for an extremely wide variety of disease control applications.” (Kowalski, 2009).

(Figure 1. Radiology Department In Hospital For UV-C High Power Ultraviolet Disinfection)

Portable UV germicidal lamps have an excellent potential to disinfect Radiological Instrumentation Probes and Personnel Contamination Monitors

(PCMs), inactivating 99.999% of pathogens on solid, non-porous surfaces. The technology is proven against SARS and MERS Coronaviruses.

An XtraLight® UV-C Handheld Ultraviolet Disinfection System, model #UVCH240254WH, was purchased and tested August 26-27 and September

2-3, 2020. Tests were conducted to determine the feasibility of using this lamp to rapidly disinfect radiological instrumentation probes and

Personnel Contamination Monitors (PCMs). The irradiance readings, using a NIST-traceable radiometer, demonstrated that a sufficient fluence, or

radiant dose of Ultraviolet-C (UVC) to kill or inactivate 99.999% of many pathogens, would require the following times seen below on table 1.

(There was no response by the contamination monitoring instruments to the UVC, demonstrating that the instruments could be disinfected while

energized and immediately returned to service.)

Table 1. Disinfection Times for Radiological Equipment using a UV-C Handheld

Of the studies of germicidal effectiveness of UVC, the ambulance test is the most applicable. It was found that a dose of 52.6 mJ/cm2 was required

to inactivate at least 99.9% B. subtilis spores on a solid surface which would inactivate 99.999% of many pathogens on a solid surface. This value of

52.6 mJ/cm2 will be the standard disinfection dose to be required when evaluating any UVC lamp.

Find: Time of irradiation to achieve 52.6 mJ/cm2.

Since 1 Joule = 1 Watt-second, find time to reach 52.6 mW-sec/cm2.

(52.6 mW-sec/cm2)/(5.54 mW/cm2) = 9.5 sec

This chart displays the mW/cm² (Ultraviolet-C Irradiance) per second when held 1.5" from calculation paper with the x and y values being inches from the dead center of the lamps.

Table 1.1 Irradiance Map of Lamp with Paper Base. (Units: mW/cm² Inches from dead center of lamp)

                    Terms and Fundamental Quantities:

                                            Ultraviolet Radiation:

The full spectrum of ultraviolet radiation (UVR) can be classified into three

groups based on wavelength: ultraviolet A (UVA) (400-315 nm), ultraviolet B

(UVB) (315-280 nm), and ultraviolet C (UVC) (280-100 nm).” (Chang) UVA is

commonly known as black light and causes an immediate tanning effect to the

skin, UVB is the wavelength that causes suntan and sunburn, and UVC is the

wavelength that provides germicidal action.

(Figure 1.1 [when in] viruses, uracil takes the place of thymine. Inactivation of RNA viruses involves

cross-linking between the uracil nucleotides and the creation of uracil dimers.)

“UV wavelengths inactivate microorganisms by causing cross-link between

constituent nucleic acids. The absorption of UV can result in the formation of

dimers in DNA, which can lead to mutations or cell death. The primary dimers

formed in DNA by UV exposure are known as thymine dimers. The lethal effect

of UV radiation is primarily due to the structural defects caused when thymine

dimers form but secondary damage is also produced by cytosine dimers.”

(Kowalski, p. 21) See Figure 1.1 “In RNA …[when in] viruses, uracil takes the place

of thymine. Inactivation of RNA viruses involves cross-linking between the uracil

nucleotides and the creation of uracil dimers.” (Kowalski, p. 23)

“Worst Case” Threshold Limit Values (TLVs) for unprotected eyes and skin were

measured at 2, 4, 5, 6, 7, 8, 9, and 10 feet, with the unprotected worker staring

directly at the lamp output. TLVs were as follows:

     - 2 feet: 8 seconds

     - 4 feet: 27 seconds

     - 5 feet: 42 seconds

     - 6 feet: 1 minute

     - 7 feet: 1 minute, 19 seconds

     - 8 feet: 1 minute, 44 seconds

     - 9 feet: 2 minutes, 15 seconds

     - 10 feet: 2 minutes, 45 seconds

Approvals

To see more information on XtraLight's UV-C products, please click here.

_________________________________________________________________________________________________________________________

References:

Alberts, B. (1970, January 01). Introduction to Pathogens. Retrieved October 13, 2020, from https://www.ncbi.nlm.nih.gov/books/NBK26917/

Berg, J. M. (1970, January 01). Amino Acids Are Encoded by Groups of Three Bases Starting from a Fixed Point. Retrieved June 01, 2020, www.ncbi.nlm.nih.gov/books/NBK22358/

(2017, December 06). SARS. Retrieved October 13, 2020, from https://www.cdc.gov/sars/index.html

(n.d.). Middle East Respiratory Syndrome (MERS). Retrieved October 13, 2020, from https://www.cdc.gov/coronavirus/mers/index.html

(n.d.). SARS-CoV-2 Viral Culturing at CDC. Retrieved October 13, 2020, from https://www.cdc.gov/coronavirus/2019-ncov/lab/grows-virus-cell-culture.html

(2020, September 02). NIOSHTIC-2 Publications Search - 20034387 - Ultraviolet germicidal irradiation - current best practices. Retrieved October 13, 2020, from https://www.cdc.gov/niosh/nioshtic-2/20034387.html

Cournoyer, M. (2018, March 01). Contamination control monitoring at the Los Alamos National Laboratory's Plutonium Facility. Retrieved October 13, 2020, from https://www.osti.gov/servlets/purl/1492670

Duan SM, Zhao XS, Wen RF, et al. Stability of SARS coronavirus in human specimens and environment and its sensitivity to heating and UV irradiation. Biomed Environ Sci. 2003;16(3):246‐255 https://pubmed.ncbi.nlm.nih.gov/14631830/

Jingwen C, Li L, Hao W. (2020). Review of UVC-LED Deep Ultraviolet Killing New NCP Coronavirus Dose. In Technology Sharing. (Hubei Sheng Technology Co., Ltd. www.researchgate.net/publication/339887436_2020_COVID

19_Coronavirus_Ultraviolet_Susceptibility

Kowalski, W., Bahnfleth, W., Raguse, M. and Moeller, R. (2020), The cluster model of ultraviolet disinfection explains tailing kinetics. J Appl Microbiol, 128: 1003-1014.

doi:10.1111/jam.14527 https://sfamjournals.onlinelibrary.wiley.com/doi/abs/10.1111/jam.14527

Kowalski, Wladyslaw & Walsh, Thomas & Petraitis, Vidmantas. (2020). 2020 COVID-19 Coronavirus Ultraviolet Susceptibility. 10.13140/RG.2.2.22803.22566. https://www.researchgate.net/publication/339887436_2020_COVID

19_Coronavirus_Ultraviolet_Susceptibility

Lodish, H. (1970, January 01). Viruses: Structure, Function, and Uses. Retrieved June 01, 2020, https://www.ncbi.nlm.nih.gov/books/NBK21523/

Lytle, D. C., & Sagripanti, J. L. (2008, March 18). Predicted Inactivation of Viruses of Relevance to Biodefense by Solar RadiationC. David Lytle. Retrieved May 29,

2020, https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/1128/report/F

Organization, W. H. (2020). Coronavirus. Retrieved June 01, 2020, https://www.who.int/health-topics/coronavirus

Phan, M., Ngo Tri, T., Hong Anh, P., Baker, S., Kellam, P., & Cotten, M. (2018, December 15). Identification and characterization of Coronaviridae genomes from Vietnamese bats and rats based on conserved protein domains. Retrieved June

01, 2020,  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6295324/

Ren Y, Li L, Jia YM. New Method to Reduce COVID-19 Transmission - The Need for Medical Air Disinfection is Now. J Med Syst. 2020;44(7):119. Published 2020 May 21. doi:10.1007/s10916-020-01585

8 https://pubmed.ncbi.nlm.nih.gov/32440893/

Walker CM, Ko G. Effect of ultraviolet germicidal irradiation on viral aerosols. Environ Sci Technol. 2007;41(15):5460‐5465. doi:10.1021/es070056u https://pubmed.ncbi.nlm.nih.gov/17822117/