Carbon monoxide deaths at Snaefell Mine

Background. The Great Snaefell Mine, located in the Laxey Valley, was a zinc mine formed in 1871. By 1897, working conditions had deteriorated due to insufficient ventilation at significant depths. The mine's lowest shaft depth was recorded as 171 fathoms, creating hazardous environments for the miners operating within the complex.

Incident. In early May 1897, dynamite had been used to extend the workings in the lowest part of the mine, and on Friday 7 May the government inspector, along with the mine captain, inspected the mine to check there was enough ventilation. Despite these precautions, the disaster was caused by carbon monoxide produced by burning timber, and several miners died. Those at the top got out without too much difficulty, but others arrived at the surface in a state of near collapse, and it soon became apparent that a large number of the miners who had made the descent were unable to return. A later attempt to recover the body of Robert Kelly also failed: 13 miners descended the shaft despite the risks, but after several hours they returned to the surface without recovering it.

Investigation. Physiologist John Scott Haldane examined blood samples and air from the mine. The blood showed a pink tint characteristic of carbon monoxide poisoning, with hemoglobin estimated to be 80 percent saturated. Air samples collected on 12 May confirmed the presence of the gas responsible for the deaths.