Monolayers of a ruthenium complex derivative are formed on thin layers of Belousov-Zhabotinsky (BZ) reaction solutions to visualize specific pattern formation at the liquid-monolayer interface. A combination of luminescence and transmission detection allows simultaneous observation of wave characteristics both in the monolayer and in the BZ solution. Luminescence images of the monolayer coupled with the Mn-catalyzed BZ reaction show that the geometry of propagating spiral waves is extremely sensitive to atmospheric conditions, while spatiotemporal patterns are almost unaffected in bulk solution. A clear transition from the usual spirals to wavelength-doubled spiral fragments is found in the monolayer when the system is kept under an air atmosphere.