Scientists support the use of ultraviolet light to reduce SARS-CoV-2 transmission indoors

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Pathways of viral infection in everyday life shown in a simplified scheme (top) and illustrated by pictorial descriptions of exposure to virus in everyday activities (bottom). Placement of UV-C light sources in ventilation systems and rooms not in use, without direct optical paths to humans, helps reduce virus propagation. Image sketches by Nacho Gaubert.

An international team of researchers advocates the use of UV-C light in indoor spaces as a way to reduce the transmission of SARS-CoV-2 viruses. This solution meets the requirement for fast, scalable and affordable implementation to fulfil the need to disinfect work spaces such as offices, schools, healthcare facilities and public transport, to name a few.

Dec 09, 2020

The SARS-CoV-2 outbreak is posing an extraordinary challenge that requires swift worldwide action for the massive deployment of affordable and ready-to-apply measures to drastically reduce the probability of transmission in indoor spaces and eventually return to conventional activities such as working at the office, going to school or even attending entertainment events.

Studies show that the virus follows two main paths. Firstly, the virus can be transmitted through air in droplets exhaled by infected individuals and inhaled by healthy individuals. Secondly, it can be deposited on surfaces from either exhalations or hand contact. Several measures are now being adopted to help prevent the transmission of the disease. The most common are face masks and other physical barriers that have proven to be highly effective but that depend on the compliance of the population, however.

A wide range of studies suggests that the virus has a much higher transmission rate in indoor spaces than it does outdoors. Filters and chemicals have been presented as possible solutions to minimise this problem, but even though these are efficient solutions that reduce the concentration of contaminated particles and droplets in ventilation systems their installation may be costly and time-consuming. In addition, chemicals such as ozone are very effective for virus disinfection, but they are harmful to humans if they are misused.

In this context, in a study recently published in ACS Nano the ICREA Professor at the ICFO Javier García de Abajo, in collaboration with ICREA professors Andreas Meyerhans (Universitat Pompeu Fabra) and Joan Rosell-Llompart (University Rovira i Virgili), together with professors Rufino Javier Hernández (University of the Basque Country), Ido Kaminer (Technion) and Tilman Sanchez-Elsner (University of Southampton), who are experts in the fields of virology, immunology, aerosols, architecture and physics, have surveyed possible methods for preventing SARS-CoV-2 propagation in indoor spaces. Following this survey, they advocate one measure that they believe to be particularly efficient, easily deployable and economically affordable: virus inactivation by ultraviolet light.

The study gives information on currently available UV-C sources, such as fluorescent lamps, microcavity plasmas and LEDs, and emphasises that, by irradiating this type of light inside the ventilation systems of buildings and in shared indoor spaces while they are not in use, it is possible to quickly and efficiently deactivate airborne and surface-deposited SARS-CoV-2 viruses.

They also explore costs and investments in deploying such technology and argue that a global capital investment of a few billion dollars in UV-C sources could protect in the order of ~109 indoor workers worldwide.