It is shown that when rate constants confirmed by recent laboratory studies are used in photochemical O3 calculations unacceptably high O3 concentrations and total O3 amounts are obtained. In order to account for this disagreement, an investigation has been made to see whether reactions between O3 and excited forms of molecular and atomic oxygen are of importance in the atmosphere, following recent laboratory work in this field. It was found that excited molecular oxygen may be neglected in the O3 reaction scheme but that reactions between O3 and O(1D could be of importance in the stratosphere. The importance of this reaction depends very markedly on the rate of deactivation of O(1D in the atmosphere, and a conflict of requirements exists between the O3 and 6300 Å airglow values for this rate. Hence, in view of this conflict, the photochemical O3 problem has been left unresolved.