PARTICLE RADIUS (cm) 1 100 150 200 HEIGHT KILOFEET 250 Fig. 6 -- Limits of fully effective collection for diffusion and impaction for 10-micropore (a =5x 10-4 cm) and 100-micropore (a = 5x 107% cm) filters. The flow conditions and other filter characteristics assumed are given in the text. Diffusion collects all particles smaller than its limit, while impaction collects all particles larger than its limit. 144