Sonja Žabkar and Katarina Fras underwent three-week hands-on training at Swansea University Medical School, Swansea, Wales, where they gained new knowledge on working and handling the in vitro cell co-culture lung model. They saw how to handle the co-cultures in the inserts, such as media change, treating the co-cultures with chemicals, establishing an air-liquid interface (ALI), where the cells are apically exposed to air, harvesting, and fixing the cells for further experiments. They also managed to touch the principles of micronucleus assay with fixed cells and its analysis on the Metafer system.