NIOSH Mining Safety and Health Research

Since 1988, 18 incidents have been documented in the United States and Canada in which carbon monoxide (CO) is suspected to have migrated through ground strata from blasting operations into nearby confined spaces. There have been 39 suspected or medically verified CO poisonings and 1 fatality. The most recent incident occurred in Kittanning, Armstrong County, PA. In this incident, blasting fumes traveled 400 ft from a coal strip mine into a home, poisoning a couple and their baby. Fortunately, all three recovered following treatment in a hyperbaric chamber.

To better understand the factors that contribute to CO production in blasting, PRL conducted lab studies to identify key factors that influence CO production by explosives. Fumes measurements were obtained in the 12-ft-diam sphere for the detonation of several commercial explosives commonly used in trench blasting operations. Tests of several explosives were done in an oxygen-poor, argon-rich atmosphere. Results were compared with those for the same explosive detonated in air. Explosive formulation, explosive wrapper, aluminum addition, oxygen balance, and density were examined and found to be major contributing factors to CO production. The results show the importance of good quality control in the manufacturing of explosives. Unfortunately, preliminary results suggest that quality control in explosive manufacturing may be suffering as the highly competitive blasting market forces manufacturers to find ways to keep down explosive prices.

Evaluation of explosive fumes production in an argon atmosphere may prove to be a good simulation of explosive detonation in the low-oxygen environment at the bottom of a borehole. All the other larger scale tests of fumes production involve detonation of explosives in air. Measuring fumes production in air does not reliably characterize the actual toxic fumes production because it permits afterburning and oxidation of explosive products, which does not occur in boreholes.