LedRise LED Lighting Blog

Fact Sheet on UV Disinfection for COVID-19

The scientific community now strongly believes that UV disinfection technologies can play a role in a multiple barrier approach to reducing transmission of the virus that causes COVID-19, SARS-CoV-2, based on current disinfection data and empirical evidence. UV is a well-known disinfectant for air, water and surfaces that, when used correctly, can help reduce the risk of infection from contact with the COVID-19 virus. Leading experts from around the world have gathered to develop a guide to the effective use of UV technology as a disinfection measure to reduce transmission of the COVID-19 virus.

It should be noted that "UVC", "UV disinfection" and "UV" as used here and in the scientific, medical and technical literature refer specifically and importantly to UVC light energy (200-280nm light) in the germicidal range, which is not the same as UVA and UVB radiation used in tanning beds or sun exposure.

Facts about UV and COVID-19

Can UVC help prevent the transmission of COVID-19 by reducing contamination?

Based on the available evidence, scientists believe so. Here's why:

• UVC light has been used extensively for more than 40 years to disinfect drinking water, wastewater, air, pharmaceutical products and surfaces against a whole range of human pathogens. All bacteria and viruses tested to date (many hundreds over the years, including other coronaviruses) respond to UV disinfection. Some organisms are more sensitive to UVC disinfection than others, but all tested to date respond at the appropriate doses. For info about the Fluence (UV Dose) Required for up to 99% disinfection from Viruses, Bacteria, Protozoa and Algae , based on 413 reasearch papers, read our related article.
• UVC disinfection is often used in conjunction with other technologies in a multi-barrier approach to ensure that any pathogen that is not 'killed' by one method (e.g. filtering or cleaning) is inactivated by another (UVC). In this way, UVC could now be installed in clinical or other settings to supplement existing processes or shore up existing protocols when they are exhausted by excessive demands due to the pandemic.
• COVID-19 infections can be caused by contact with contaminated surfaces and subsequent touching of facial areas (less common than human-to-human, but still a problem)[vi]. Minimising this risk is critical as the COVID-19 virus can survive on plastic and steel surfaces for up to 3 days[vii]. Normal cleaning and disinfection may leave some residual contamination that can be treated with UVC, so a multiple disinfectant approach is advisable. UVC has been shown to achieve a high level of inactivation of a close relative of the COVID-19 virus (i.e. SARS-CoV-1, tested with an appropriate dose of 254nm UV while suspended in liquid)[viii]. Scientists believe that similar results can be expected in the treatment of the COVID-19 virus, SARS-CoV-2. However, the key is to apply UVC in such a way that it can effectively reach all remaining viruses on these surfaces.
• There is widespread agreement with CDC guidance for hospitals that the germicidal efficacy of UVC is influenced by the UVC-absorbing properties of the suspension, surface or aerosol in which the organism is located, by the type or spectrum of action of the microorganism, and by a variety of design and operational factors that affect the UV dose delivered to the microorganism (https://www.cdc.gov/infectioncontrol/guidelines/disinfection).

The scientific community recognizes that in cases where the UVC light cannot reach a particular pathogen, that pathogen is not disinfected. However, in general, by reducing the total number of pathogens, the risk of transmission is reduced. The total pathogen load can be significantly reduced by applying UV light to the many surfaces that are easily accessible, as a secondary barrier to cleaning, especially under hurried conditions. This would be a relatively simple matter of illuminating relevant surfaces with UVC light, e.g. the air and surfaces around rooms and personal protective equipment.

UV light, specifically between 200-280nm[i] (UVC or the germicidal range), inactivates (aka, "kills") at least two other coronaviruses that are close relatives of the COVID-19 virus: 1) SARS-CoV-1[ii] and 2) MERS-CoV[iii] [iv] [v]. An important caveat is that this inactivation has been demonstrated under controlled conditions in the laboratory. The effectiveness of UV light in practice depends on factors such as exposure time and the ability of UV light to reach viruses in water, air and in the folds and crevices of materials and surfaces.

Are UVC disinfection devices safe?

Like any disinfection system, UVC devices must be used properly to be safe). They all produce varying amounts of UVC light with a wavelength of 200nm-280nm. This UVC light is much "stronger" than normal sunlight and can cause a severe sunburn-like reaction on your skin. The target tissue in the eye would be the cornea (and not the retina). The effect on the cornea is called photokeratitis, which is also known as sweat flash or snow blindness, so it's like sunburn of the eye. It is unlikely that any of the UVC light will pass through the cornea and then the lens to reach the retina as it is a short wavelength (i.e. high frequency).

Some devices also produce ozone as part of their cycle, others produce light and heat like an arc welder, still others move during their cycle. Therefore, general machine and human safety must be considered with all disinfection equipment and these considerations should be addressed in the operating manual, user training and relevant safety regulations.

Are there performance standards and UVC validation protocols for UV disinfectors?

Given the wide range of UVC devices marketed for disinfection of air, water and solid surfaces, the lack of uniform performance standards and the widely varying degree of research, development and validation testing performed on different devices, the scientific community strongly recommends that consumers exercise caution when selecting devices and look for evidence of third-party testing and certification of device materials and electrical components by well-known organizations such as NSF, UL, CSA, DVGW-OVGW or other international requirements.

For UVC devices intended to inactivate air and solid surfaces in the healthcare industry,the scientific community is working intensively with national standards organizations in the lighting and healthcare industries to develop disinfection test standards[x]. The goal is to develop guidelines that will help healthcare providers worldwide select the best possible technologies for their facilities in the fight against multidrug-resistant organisms and other pathogens[xi], such as the COVID-19 virus.