What is the potential consequence of having too much methane present when firing explosives?

The presence of too much methane when firing explosives can indeed lead to ignition and uncontrolled fire. Methane is a highly flammable gas, and in high concentrations, it can create a volatile atmosphere, especially in confined spaces. When detonating explosives, the resulting heat and shock waves can initiate combustion of the methane, leading to a fire that can spread uncontrollably. This scenario presents significant safety risks, especially in mining or construction settings where explosives are frequently used, as the presence of additional flammable gases can exacerbate the destructive potential of an explosion or cause hazardous conditions.

The other options suggest effects that may not accurately represent the risks associated with excessive methane. While it's true that methane could influence the effectiveness of an explosion or potentially fail to detonate properly, the primary concern remains the increased risk of ignition and the subsequent hazards of an uncontrolled fire. Thus, highlighting the danger of uncontrolled fire emphasizes the importance of monitoring environmental conditions and gas concentrations prior to explosive use.