Empirical evidence obtained for CO at room temperature, which supports the use of average absorption coefficients for entire vibration‐rotation bands, is examined. In Sec. II the existence of an average apparent absorption coefficient for data obtained with inadequate spectral resolution is demonstrated. In Sec. III semiquantitative evidence at elevated total pressures and small optical densities for the use of a constant absorption coefficient equal to the ratio of integrated absorption to effective band width is described. These results serve as direct support for a proposed simplified method for radiant‐heat‐transfer calculations.