In a continued study on the generation of toxic fumes by commercial explosives the influence of some variations in a nitroglycerine (NG) based semigel explosive formulation was investigated in a cylindrical laboratory fume study chamber with a capacity of 6 m(3). The influences of varying quantities of wax coated cartridge wrapper, the grain sizes of ammonium nitrate and the sampling time interval on the generation of oxides of nitrogen (NO,) and carbon monoxide (CO) in the detonation products were studied by analyzing a large number of sample data. A graphical analysis of the resulting fume data led to interesting findings, indicating the possibility of designing NG-based semigel explosives with a better fume quality through the selection of coarser grains of AN rather than finer grains as ingredient and smaller quantities of waxed wrapping paper as cartridge. A further reduction of the total toxic fume level in the post blast atmosphere may be achieved with lapse of time.