A method for removing a contaminant from an environment is described comprising the steps of: (i) heating a reduced and passivated getter material containing crystallites of a metal in elemental form encapsulated by a layer comprising an oxide of the metal to a temperature in the range (TT−X) to (TT+Y), where TT is the Tammann temperature of the metal in elemental form in degrees Centigrade, X is 400 and Y is 200, to form an activated getter material having active surface for contaminant removal and (ii) exposing the activated getter material to the environment containing the contaminant.