Marko Križmančić was visiting Spain from 8th to 11th May 2023, where he participated in setting up air quality sampling experiments for the WatchPlant project. The project partners from CSIC-IRNAS and CSIC-IDAEA placed tomato and ivy plants in three different air quality measuring stations located in Barcelona and Vic. These locations were selected specifically to monitor background pollution in suburban, urban, and high-traffic density areas. In a couple of months, the responses collected from plants in the experiment will be matched with data from air quality stations to create more precise models for future bio-hybrid sensors.