A novel source of carbon monoxide poisoning: explosives used in construction.
Decker-JA; Deitchman-S; Santis-L
American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia. Fairfax, VA: American Industrial Hygiene Association, 1998 May; :47-48
This report describes three cases of carbon monoxide (CO) poisoning in a manhole, including one fatality, from CO migrating through soil after nearby use of explosives. A municipal sewer project involved installation of new pipes and manholes. Employees entered and exited a new, unconnected, manhole several times without incident. Work was interrupted when 265 pounds of nitroglycerin-based explosive in boreholes 15-feet deep were detonated 50 feet south of the manhole to break-up underlying rock. A worker who descended into the manhole 45 minutes after the explosion collapsed within minutes, and two co-workers descended into the manhole to rescue him. One rescuer retrieved the unconscious worker, and the other rescuer died in the manhole. All workers had elevated carboxyhemoglobin levels. In the subsequent investigation, air monitoring was conducted with real-time instruments and air samples were taken in Tedlar bags. Laboratory analyses of air samples taken 11 feet below the surface showed 1910 ppm CO, 19.5% oxygen, and 3% carbon dioxide. Direct reading instruments indicated surface CO concentrations near zero and highest concentrations near the bottom. Subsequent chamber tests on sample explosive yielded 27 liters CO per kilogram detonated. This suggests the surface blast could have produced about 3250 liters CO. We believe the CO in this fatal accident was released from the nearby explosion and migrated through soil and fractured rock into the manhole. The blasting and construction industries should be made aware of this previously unrecognized route of CO exposure. Additionally, confined-space procedures and training are needed to prevent future accidents.
Risk-analysis; Air-contamination; Air-quality; Air-sampling; Air-samples; Gas-indicators; Gas-sampling; Explosive-hazards; Explosive-atmospheres; Explosion-venting; Construction; Construction-industry; Construction-workers; Blasting-agents; Poison-gases; Confined-spaces
American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia