Asymmetry of the atmospheric oxygen 118 GHz line due to the air pressure shift of the center frequency of this line is predicted, and estimations are given for some observation modes. The observability of this atmospheric line asymmetry by the appropriate instruments is shown. The necessity of considering the pressure shift in atmosphere propagation models such as the well-known millimeter wave propagation model (MPM) is demonstrated. Line shift as a new source of information is discussed. At the moment, 183 GHz water and 118 GHz oxygen lines are the only known microwave lines with appreciable air pressure frequency shift that are used for atmosphere sounding. The possible directions of further studies are outlined.