This study assessed the dispersion of perchlorate and dioxins and furans (PCDD/PCDF) residues following the use or demilitarization by blow-in-place of the Groundburst Simulator (GB) C1A1 and the Thunderflash (TF) C1A1commonly used in the Canadian Armed Forces (CAF). The amount of unburned perchlorate residues per pyrotechnic device reached 0.8 and 43mg for the regular use of TF and the GB, respectively. Their demilitarization by blow-in-place operations led to higher dispersion of unburned perchlorate residues, up to 6 and 2300mg per TF and GB, respectively. Very high deposition rates were obtained for water-soaked items: up to 460mg per TF and up to 6600mg for the GB. Dioxins and furans reached a maximum of 1 pg of Toxic Equivalent (TEQ) for the regular use, and 9 pg TEQ for the BIP operations. Based on these results, it is recommended to find alternate ways to demilitarize malfunctioning and weathered items found in military ranges and training areas.