  We investigate collisional decay of the axial charge in an electron-photon
plasma at temperatures 10 MeV - 100 GeV. We demonstrate that the decay rate of
the axial charge is first order in the fine-structure constant $\Gamma_{\rm
flip}\propto \alpha m_{e}^{2}/T$ and thus orders of magnitude greater than the
naive estimate which has been in use for decades. This counterintuitive result
arises through infrared divergences regularized at high temperature by
environmental effects. The decay of axial charge plays an important role in the
problems of leptogenesis and cosmic magnetogenesis.
