A low-speed impaction device consisting of a set of impactor plates connected in series or in parallel for use in sampling both solid and liquid particles suspended in the atmosphere. The diameters of the nozzles or slits above each impactor plate are designed in such a manner that each sampling plate collects particles of predominantly one size range. This method is used to obtain different size fractions of ambient particles in the range of diameters ∼ 0. 5 to 30 μm.