Most of the explosions were caused by firedamp ignitions followed by coal dust explosions. The explosion was caused by a firedamp explosion. It would have ignited the firedamp, exacerbated and fuelled by coal dust in the air. At a certain concentration the gas (firedamp or methane) burned but did not explode. Coal mining was very dangerous owing to the presence of firedamp in many coal seams. This time the firedamp leaking from the void above the goaf was ignited. At Wallsend in 1818 lamps were burning red hot (indicating significant firedamp). In the presence of firedamp the flame intensifies. Such engines could not be used in mines with firedamp problems. Thus low pressure increases the risk of firedamp accumulating. Despite wearing respirators, several rescuers were overcome by the effects of firedamp. Davy however performed his experiments with samples of firedamp collected from pits. The area above the goaf was inadequately ventilated and acted as a reservoir for firedamp. The cause was assumed to have been the ignition of firedamp by a safety lamp. In addition, the shaft provided vitally important fresh air ventilation and extraction of the firedamp.