Location and physical properties in the MIR line-emission regions of the EX Lupi disc model. Upper row: Line-emitting regions of different molecules in two different spectral bands in the best-fitting EX Lupi model. The left upper plot considers λ = 4-07 µm, and the right upper plot λ = 13-17 µm. The white lines at the bottom of the plots mark the location where the vertical continuum optical depth is one, considering an average of the wavelengths of all water lines in the considered wavelength region. The bottom row shows the corresponding gas temperatures (left) and the carbon-to-oxygen ratio C/O in the gas phase (right). C/O = 0.46 is constant by assumption, except for the region where water ice is found to be stable, where C/O instantly jumps to very large values of >1000.