The team’s efforts focused on evaluating the nature of the solid surface and the germicidal effectiveness of this radiation. The materials selected were those generally found in homes. The UA researchers inoculated organisms on smooth, low-porosity ceramic or plastic surfaces. In this case, as confirmed by José Luis Todolí, it was verified that microbial cultures on samples taken from these surfaces before irradiation give rise to the development of several colonies of microorganisms (see Figure 1). However, when these surfaces are irradiated using a low-power source, the analysis results show that the colonies do not develop.
Rough surfaces were also studied, such as types of terrazzo generally employed for outdoor paving. These materials are very difficult to treat using UV radiation, as organisms can be protected from radiation in their pores. That is a major problem when it comes to sterilising solid surfaces, since the presence of pores clearly undermines their safety. However, according to the data obtained for porous surfaces, UV radiation is also beneficial, with a remarkable reduction in the number of colonies once the surface is exposed to UV light. Irradiating the surfaces for 30 seconds already produces positive results.
The researchers confirm that, at a considerable distance, UVC treatments do not lose effectiveness. This is important, as the surfaces were treated from a significant distance. Therefore, they conclude that under sufficiently optimised conditions the effectiveness of UVC radiation does not seem to decrease due to intensity losses caused by ambient air.
Another aspect investigated by the team was the great concern over the potential health effects of repeated use of face masks, as microorganisms can grow on their surfaces and cause skin and other problems. As for the treatment of personal protective equipment, in surgical and FFP2 masks the researchers determined that, once the surfaces of porous materials like those used for making these masks have been irradiated, microbial activity is completely inactivated. This can be very important in those situations in which face masks are reused. Therefore, it could be possible to reduce consumption and increase the safety of certain face masks by extending their lifespan after treating them with UVC radiation.
Finally, José Luis Todolí’s team has proposed evaluating the germicidal properties of UVC light for disinfecting nitrile gloves. The use of disposable gloves poses serious environmental problems, since a very high amount of waste is generated. In fact, the large amount of plastic waste employed in the late 20thcentury and still present on the coast of Alicante has recently captured the media’s attention. As part of this project, the surface of these gloves, previously contaminated with microorganisms, was exposed to radiation (see Figure 2). Again, “excellent results have been observed,” Professor Todolí points out. It is thus concluded that, after a short exposure to UV light, these gloves can be used several times with a minimised risk of microorganism contamination. According to experimental data, in this case good results can be obtained after a very short exposure, of just 5 seconds.
The global goal of the project is to eliminate bacterial and viral populations from solid surfaces through UV radiation. It is estimated that the team’s work on coronavirus could give results in a couple of months. The research team is made up of José Luis Todolí, principal investigator (PI); Raquel Sánchez and Salvador Maestre, from the area of Analytical Chemistry; and Ana Beltrán and Soledad Prats, from the area of Nutrition.
Universidad de Alicante Carretera de San Vicente del Raspeig s/n 03690 San Vicente del Raspeig Alicante (Spain)