One of the unresolved questions related to the mechanism of action of light negative air ions (reactive oxygen species) produced by air ionizers upon humans and animals is transmission of these short-living chemical species upon long distances from the place of their origin. We discovered the phenomenon which may probably resolve this problem. When a thin layer of water hydrating a hygroscopic surface absorbs rare UV-photons capable to split water molecules a flash of photon emission in UV- and visible regions of spectrum is observed. This flash (or oxygen-dependent oxidative processes underlying it) initiate reactions accompanied with generation of electronic excitation in the air contacting water film. Excitation propagates through the air at macroscopic distances, and the level of propagating excitation increases with elevation of air humidity. When air humidity exceeds 50% air excitation gains oscillatory-wave character. This phenomenon may endow into the mechanism of action of air ions generated artificially, and also into some natural processes where ordered water films may form and the latter may serve targets for energy impulses initiating oxygen-dependent oxidative processes in these films.