What is the minimum quantity of air required at all working faces in a working section?

The minimum quantity of air required at all working faces in a working section is established to ensure adequate ventilation for the safety and health of miners. Providing sufficient airflow is crucial for diluting and removing harmful gases, such as methane and carbon dioxide, as well as dust that can impair visibility and air quality.

Specifically, the requirement of 3,000 cubic feet of air per minute is a standard that helps maintain a safe breathing atmosphere for workers. This volume of air is generally sufficient to ensure that any contaminants are effectively diluted and that miners can work safely without facing immediate health risks from the environment.

In comparison to the other options, 2,000 cubic feet may not provide enough air to maintain air quality, and higher amounts like 4,000 or 5,000 cubic feet may exceed what is necessary for standard operations, potentially leading to unnecessary energy use or ventilation system costs. Thus, 3,000 cubic feet strikes a balance between safety and practicality in mine ventilation systems.