Ultraviolet light has begun to be used in countries that are already lifting social distancing restrictions to disinfect public spaces exposed to SARS-CoV-2, and thus stop the spread of Covid-19. In Peru, a team of researchers associated with the Universidad Nacional Agraria La Molina is developing an air purification system using this technology.

The proposal is one of the winners of the Innova-Covid-19 Challenge, for which it has financing of 275 thousand soles from Innóvate Peru and 40 thousand soles from the Tecnofood company.

In order to guarantee the effectiveness of the system, called SaniAir, the researchers use type C ultraviolet light (UV-C) -which is manufactured artificially-, since natural UV-C does not reach the surface of the Earth, because it is absorbed in the stratosphere by the ozone layer.

Researcher Álvaro Tello Loli, project coordinator, explained that the SaniAir system works as a filter, made up of an ultraviolet light (UV-C) lamp, which operates at a frequency of 254 nanometers.

This is contained in a stainless-steel cover, which is connected to an extractor, which allows the “contaminated” air to enter the interior of this space where it is exposed to the ultraviolet disinfectant light, generated by the lamp. Subsequently, the purified air is returned to the outside environment.

“That way you can get a system at an affordable cost using only the lamps necessary to deactivate the virus,” said Tello Loli. He adds that the team of researchers points to a system “ready to plug in”, which can be activated by means of a security switch, for that reason they are seeking international validation so that this filter is used while people are in the environment, at the same time that the air is being purified, since there is no direct exposure to radiation.

How does the system work?

UV-C light is short-wave and its frequency fluctuates in the range of 100 to 280 nanometers. The other two types of ultraviolet light are in the following range: ultraviolet B (UV-B) has a wavelength ranging from 280 to 315 nanometers, and it is not very present on the earth’s surface, although it is artificially used. for tanning beds. Ultraviolet A (UV-A) light oscillates at a radiation frequency ranging from 315 to 400 nanometers. This is the most common in the environment, since it is not retained in the atmosphere.

“If UV-C light managed to pass the atmosphere, there would simply be no life on the planet. But, just as it is capable of ending human life, UV-C light also breaks down the RNA and DNA molecules of the virus, thus inactivating its ability to make more copies of itself and preventing contagion, “he said. For his part, the microbiologist from the Universidad Nacional Mayor de San Marcos (UNMSM), Jorge Gavidia, representative of TersusMax, a Peruvian company that also aims to develop ultraviolet C radiation equipment, whose proposal is that these be manipulated through devices digital to avoid human contact.

Although UV-C light, discovered in 1878, has been used for decades to disinfect water, air and surfaces, in recent years it has been shown to be effective in reducing the spread of the SARS-CoV and MERS-CoV coronaviruses. “For this reason, scientists now recommend its use to stop the contagion with the new coronavirus,” said Gavidia. It is important to note that ultraviolet light equipment, marketed for direct user handling (with UV-A or UV-B light), has not been shown to have a germicidal effect. Therefore, referring to UV-C light, the World Health Organization (WHO) has issued a severe warning to people who intend to use this radiation to sterilize their hands or any other part of their skin.