K5 emulsions 10 mu m thick were exposed at various depths in a perspex phantom to a 70 MeV pi ^- meson beam and counts taken of the tracks in emulsion volumes 7*7*10 mu m³. Data are presented on the number of track events and also the total number of grains associated with each event in each of four categories spanning the LET range of the secondary particles. The number of heavy tracks (category 4) shows an increased incidence in the region of the stopping pi ^- mesons while the number of single grains (category 1) decreases with depth. Categories 2 and 3 (grain clusters and light tracks) are approximately constant with depth. An estimate of the grain sensitivity is obtained by taking the proton as representative of the whole range of secondary particles.