Abstract: Holder for an annular filter includes a support frame or basket with a flared portion at its upper end which cooperates with the inner leg of an inverted U-shaped sealing ring to clamp the upper end of the filter. The sealing ring has its outer leg seated on a sealing gasket positioned on top of a support plate surrounding an aperture through which the filter is lowered during operation of a particle collection apparatus. The holder is replaceably sealed in position by screwing a pair of threaded rings together to force the flared portion downwardly. The diameters of the various parts are larger than the aperture to prevent them from being dropped through the aperture and the overall design is such that the filters can be replaced from the upper clean side of the collection apparatus rather than the lower dirty side.