For the first time the 118-GHz line of the oxygen molecule was investigated in the laboratory under a real atmosphere. The experiment was carried out by modern resonator spectroscopy methods on the laboratory air at atmospheric pressure. The shape of the line under the real atmosphere was found to fit the Van Vleck-Weisskopf profile within experimental accuracy. The air broadening parameter value was defined as 2.14+/-0.07 MHz/Torr. The observed atmosphere oxygen line central frequency was found to be shifted down at about 150 MHz from the line center measured at low pressures, which gives a value of -0.19+/-0.08 MHz/Torr for the air shift parameter. A comparison with previous investigations is presented and reprocessing of some experimental results of other authors was carried out. Results of reprocessing agree with the findings of the present paper. Copyright 2001 Academic Press.