Abstract: A separator system has a plurality of separator stages (11, 12, 13) and operates to remove particulates from air, particularly in the inlet to an engine. Each stage includes a plurality of side-by-side inertial separators (26) through which the air flows and by which particulates are removed. Each stage (11, 12, 13) produces a pressure drop and the additional total pressure drop produced by each stage after the first is less than the additional total pressure drop produced by the preceding stage in an upstream direction. This allows particulates to be removed by the separator stages (11, 12, 13) alone without the use, in normal operation, of a barrier filter (14).