Electron paramagnetic resonance data demonstrate that E′δ, a radiation-induced defect consistently found in buried oxide films, can also be generated in nonburied oxides after heat treatment in a sufficiently dry ambient. The center appears in samples heated in either N2 or O2 with moisture content on the order of 1 part per million. The near equality of the number of E′δ centers in the N2 and O2 treated samples implies that the presence of O2 does not reduce the number of precursor defects. The results suggest that the center is related to a deficiency of hydrogen-related species in the ambient rather than an O 2 deficiency as has been previously suggested. © 1996 American Institute of Physics.