The University and State Library Darmstadt has been open again for the lending of books since 15 April while complying with all hygienic requirements and is thus ensuring the timely provision of academic literature to users of the library for the start of the summer semester. In order to safely offer this service, it was necessary to overcome the issue of how to disinfect media that may be contaminated when it arrives at the library. This could be when books are ordered and delivered or when they are returned by users. As a solution the library came up with the idea of using irradiation with UV-C light – a process also already used to disinfect surfaces and rooms in hospitals – to quickly and reliably disinfect books and internal mail.

UV-C light is short wave, very energetic and highly dispersed in biological material. It is used in disinfection technology because the light damages proteins, nucleic acids and amino acids and thus inactivates viruses, bacteria and microorganisms. UV-C disinfection is a purely physical process. The disinfectant effect of the ultraviolet radiation on microorganisms, bacteria and viruses is based on the destructive effect of the energetic UV-C light: The DNA of the microorganisms, bacteria and viruses on surfaces is damaged by the UV-C irradiation and the organisms are inactivated as a result.

Fortunately, the ULB was still able to purchase UV-C lamps – the delivery times lengthened considerably just after the order was placed. The lamps were used to set up a disinfection room at the Stadtmitte site in the centre of town. The lamps are set up around the room and disinfect the air and any surfaces in the room within a short period of time.

Employees wearing gloves place the books on tables and shelves, while thin documents or letters are laid out and must be turned over after half of the irradiation time. The lamps are equipped with remote controls so that the irradiation process can only be started when there are no people left in the room. This occupational safety measure is important because prolonged exposure to the highly energetic UV-C irradiation can cause skin damage or damage to the cornea.

The irradiation period is very short: Ten minutes is sufficient to inactivate organisms on the media. After they have been irradiated, the books can be used again immediately and returned to the library or loaned out. This type of disinfection room will also be set up at the Lichtweise site. The process enables the library to make the media available without long waiting times – it would otherwise be necessary to leave the books standing for three days to inactivate any possible viruses – and allows the library to operate safely and as smoothly as possible under the current circumstances.