NaCl step edges are worn under repetitive scanning by an atomic force microscope tip. The change in the wear rate when either the mechanical load on the tip or the NaCl substrate temperature is changed is well described by a thermal activation model. Two principal kinetic parameters, the activation volume and the activation energy, are extracted. The effect of low relative humidities on wear is also studied. It is found that at relative humidities (RH) less than similar to 12%, the wear rate was enhanced with respect to wear under dry nitrogen. At RH > 12%, the wear rate is suppressed. Published by Elsevier B.V.