This paper presents a detailed study of DPM dispersion in unventilated dead-end cross-cuts in an underground mine. The dispersion and dilution of DPM was measured in dead-end with time when the air is flowing in the main gallery. Parametric studies were conducted by varying the dead-end cross-cut lengths (10 m, 15 m, 20 m and 25 m), varying cross-cut angles (450, 900 and 1,350) with the main gallery and varying the velocities (0.5 m/s, 1 m/s, 2 m/s, 3 m/s, 4 m/s) in the main gallery across the cross-cuts. The results obtained show that longer time durations are required to dilute DPM for greater dead-end cross-cut lengths and angles. For 50 m dead-end cross-cut, it took five hours to reduce DPM concentration from 820 μg/m3 to 100 μg/m3. Studies also show that higher air velocity in adjacent main gallery results in shorter dilution time durations in dead-end cross-cuts. When the air velocity is below 0.5 m/s in the main gallery, no influence of DPM dilution was observed in the unventilated cross-cut for a long time.