October 14, 1913Senghenydd Colliery Disaster, the United Kingdom's worst coal mining accident, occurs, and it claims the lives of 439 miners.
The explosion was probably started by a firedamp (methane) being ignited, possibly by electric sparking from equipment such as electric bell signalling gear. The initial firedamp explosion disturbed coal dust present on the floor, raising a cloud that then also ignited. The shock wave ahead of the explosion raised yet more coal dust, so that the explosion was effectively self-fueling. Those miners not killed immediately by the fire and explosion would have died quickly from afterdamp, the noxious gases formed by combustion. These include lethal quantities of carbon monoxide, which kills very quickly by combining preferentially with haemoglobin in the blood. The victims are suffocated by lack of oxygen.