Mat (1) for mounting a pollution control element in a housing, comprising inorganic fibre material. At an edge surface (20) of the mat a plurality of fibres (30) are heat fused to form fusion volumes (90). The average number of fusion volumes per square millimetre of the edge surface is at least 100, and at least 80% of the fusion volumes have a projected size of between 10 μm and 100 μm.