A method of and apparatus for removing particulate contaminants from a gaseous stream. Broadly, the apparatus comprises a housing containing a substantially vertical granular material retention member having upstream and downstream faces, a substantially vertical microporous gas filter element, said member and element being spaced apart to provide a zone for the passage of granular material therethrough. The housing further comprises a gas inlet means, a gas outlet means and means for moving a body of granular material through said zone. In operation, a gaseous stream containing particulate contaminants passes through the gas inlet means and upstream face of the granular material retention member, passing through said member, said body of granular material, the microporous gas filter element and then out the gas outlet means. The particulates carried in the gaseous stream pass into the granular material and are retained in the body of granular material and upon the upstream face of the gas filter element. The body of granular material is moved through the zone and across the upstream face of the gas filter element to scour the upstream face and remove the collected particulates, which are carried out of the housing, such that a substantially uniform pressure drop across the apparatus is maintainable during its operation.