What must be supplied in all underground work areas?

In all underground work areas, it is critical to have mechanical ventilation to ensure the safety and health of workers. Mechanical ventilation is vital because underground environments can be confined and may lack sufficient natural airflow. This lack of natural ventilation can lead to the accumulation of hazardous gases, dust, and reduced oxygen levels, which can pose significant risks to workers.

Mechanical ventilation systems help to control air quality by actively circulating fresh air into the work area and removing contaminated air. This process aids in diluting harmful substances and maintaining an appropriate oxygen level, thus reducing the risk of respiratory problems and other health hazards associated with poor air quality.

While natural ventilation may be beneficial in some scenarios, it is not reliable in underground settings where the physical structure can restrict airflow. Options referring to electrical and chemical ventilation do not apply in a standard context; electrical ventilation does not provide fresh airflow, and chemical ventilation is not a standard term used in the industry. Therefore, mechanical ventilation is the necessary and effective approach to safely manage the air quality in underground work environments.