On the filtration of fibrous aerosols

Basic processes occurring during the filtration of fibrous aerosols are discussed. Using aerosols containing very fine asbestos fibers, the filtration efficiencies of some analytical filters — Nuclepore, Millipore and fiber filters — were investigated. The collection efficiences were determined by electron microscopy and radiolabeled asbestos fibers and were found to depend upon the pore size of the filter and on the form of the fiber of the respective aerosols. The collection efficiencies were found to lie in the range 40–99.9%. A special problem discussed concerns the orientation of fibrous particles in the vicinity of the entrances to pores in the filter.