[en] A simple relationship between the one-body and exchange current contributions to the axial charge operator may allow a separation of these amplitudes in the b-decay transition ¹⁸Ne(0⁺1)→¹⁸F(0^-0). Since the exchange current operator is related by isospin rotation to the pion exchange component of the parity nonconserving (PNC) nucleon-nucleon potential, this suggests that the PNC pion coupling can be extracted, with minimal dependence on nuclear models, from circular polarization measurements for the analog g-decay in ¹⁸F