Absorption cross sections for O2, N2, CO2, CH4, N2O, and CO have been measured at each of the lines of the atomic oxygen triplet 3S1 0-3P2,1,0. Radiation resonantly scattered from oxygen atoms at a temperature of about 300 K was used for the line source. Absorber temperatures were also near 300 K. Direct application of the Lambert-Beer absorption equation yielded pressure-dependent cross sections for carbon monoxide at each line of the O I triplet. Reasons for this apparent dependence are presented and discussed.