UV Disinfection & Lamp Evaluation

The COVID-19 pandemic has resulted in a marketplace flooded with a wide range of ineffective ultraviolet (UV) decontamination products being promoted with claims of disinfection efficacy but without any data or supporting evidence. Some manufacturers are offering long-wave UV (such as 320-400nm UVA) LED emitters into their fixtures, but those fall outside the effective germicidal range or what is considered as ultraviolet germicidal irradiation (UVGI).[1] While there is limited data on the long-term germicidal efficacy of pulsed UVA/UVB LEDs, [2] it is generally understood that rapid surface/air disinfection using long-wave UV is not possible because it falls outside the spectral absorption range of RNA/DNA. UVC and Far-UVC radiations have the potential to quickly inactivate both airborne and surface pathogens, so an effective and rapid disinfection requires UVC emitters between 220nm and 280nm corresponding to the absorption of the RNA/DNA molecule in those pathogens. There are some existing UVC (between 250-280nm) light sources on the market that rely on either low power light-emitting diodes (LEDs) or traditional mercury lamp technologies, but it is crucial to keep in mind that human DNA can be damaged by the radiation emitted from such products, which require the operation of such UV disinfection devices in the absence of humans, animals, and plants.

UV-C irradiation is very effective at preventing SARS-CoV-2 replication. However, even for users in the medical field, it is generally difficult to evaluate the efficacy of a UV-disinfecting device without proper sensors, training, and extensive testing. The team at PhosphorTech can help evaluate and compare UVC products being sold commercially in order to evaluate their efficacy in terms of surface coverage and ability to destroy pathogens. We can also offer training on the use of portable UVC sensors, various UV spectrometers, or color changing and fluorescent sensor cards that can be used as UV dosimeters. Having the ability to directly measure UV radiation and understanding the difference in required UVC dosage for different applications and pathogens is crucial for reducing the risk of contamination and improving the odds of disinfection. For example, according to research compiled by the Centers for Disease Control and Prevention (CDC) regarding UV disinfection and decontamination of N95 masks, a UVC dose at 1,000 mJ/cm² is needed to deliver a 3-log (99.9%) reduction of viruses (such as the COVID-19 strain) in N95 masks.[3] The high UVC dose recommended by the CDC for N95 masks has to do with their porous and thick filter multilayer structure, which shields viruses and pathogens from direct UVC light. On the other hand, for airborne and surface decontamination, it has been shown that a very low dose of 2 mJ/cm² in the far-UVC can de-activate >95% of aerosolized H1N1 influenza virus. [4] A UVC dosage of 10-20 mJ/cm² has been shown to achieve 99.9% disinfection (inactivation) for comparable pathogens in the SARS virus family. [5]

We can help test the effectiveness of UV disinfection by germicidal products installed at your facility or train and empower staff members to do so safely while providing the proper optical instruments and tools that work with your specific UV systems

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[1] https://link.springer.com/chapter/10.1007/978-3-642-01999-9_1

[2] https://sfamjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2672.2010.04850.x

[3] https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/decontamination-reuse-respirators.html

[4] Welch D, Buonanno M, Grilj V, et al. Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases. Sci Rep. 2018;8(1):2752.

[5] https://www.news-medical.net/news/20200608/Irradiation-with-UV-light-kills-SARS-CoV-2.aspx