What commonly leads to oxygen deficiency in mines?

Oxygen deficiency in mines is primarily caused by ventilation system failures. A properly functioning ventilation system is crucial for ensuring the circulation of fresh air throughout the mining environment. It helps to dilute and remove contaminants, including gases that can create hazardous conditions. When the ventilation system fails, the supply of fresh air diminishes, leading to a decrease in oxygen levels, which can pose serious health risks to miners working in those areas.

While overcrowding of miners can contribute to a temporary increase in oxygen consumption, it is not a direct cause of oxygen deficiency itself. High humidity levels do not typically lead to oxygen deficiency; rather, they can affect the comfort and safety of miners. Low levels of carbon dioxide are not a cause of oxygen deficiency; carbon dioxide is a byproduct of respiration, and low levels would not negatively impact oxygen availability. Thus, the failure of the ventilation system stands out as the primary factor responsible for leading to oxygen deficiency in mines.