Abstract: The present disclosure relates to methods of scrubbing of gas by exposure to electrons and apparatuses therefor. Such methods and apparatuses could be used to reduce harmful emissions created by the burning of fossil fuels, e.g. to power ships. According to one aspect there is provided apparatus for electron irradiation scrubbing, said apparatus comprising: an anode; a cathode a nanostructure located between said anode and said cathode, said nanostructure being configured to field-emit electrons in response to the presence of an electric field between the anode and cathode when a potential difference is established therebetween; and a housing coupled to said nanostructure and configured for locating the nanostructure so that it extends into a container containing gas to be scrubbed such that an interior of said container can be exposed to said electrons. According to further aspects there are provided systems comprising such apparatus and methods making use of it.