With the aid of new calculations on the transition moments between the six lowest states of O2, absorption cross sections have been calculated for several oxygen continua, including the &Agr;2∑u+← &KHgr;3∑g- and &Agr;'3Δu←a1Δg systems. Reasonable agreement is achieved with recent experimental results, the comparison indicating an overestimation ofthe theoretical transition moment for the &Agr;-&KHgr; system of 20--25%. With this adjustment, the calculated radiative lifetime for the O2(&Agr;) state is 150 ms, in close agreement with the currently used value. The &Agr;'←a and &Agr;←&KHgr; continua cross sections are of similar magnitude, indicating that absorption by O2(a) can not be a significant atmospheric process.