Lethal Hydrogen Sulfide poisoning in open space: An atypical case of asphyxiation of two workers

Hydrogen sulfide is one of the most dangerous toxic gases that has led to the deaths in confined spaces of many workers. We report an atypical case of a fatal accident of H₂S poisoning in an open space when two workers died during the opening of a hatch on a tanker truck filled with leachate water. Despite being outdoors, the two workers, were suddenly and quickly overwhelmed by a lethal cloud of H₂S, which escaped like a geyser from the hatch and hovered over the top of the tanker making it impossible for them to survive. The first operator was engulfed by the sudden flow of lethal gas near the hatch while the second worker, who came to his aid, immediately lost consciousness and fell off the tanker onto the ground. Environmental toxicological analyses were carried out on the air near the hatch and inside the tanker 2h, 20 days and 70 days after the accident. Toxicological analyses on the blood were also carried out but unfortunately, no urine sample was available. The thiosulfate, detected by GC/MS analysis after derivatization of PFBBr, was found to be 0.01 and 0.04mM/L. These values are included in the medium-low lethal values of occupational fatalities involving H₂S reported in the literature.