What is a potential drawback of relying solely on natural ventilation?

Relying solely on natural ventilation can indeed lead to unpredictability due to varying weather conditions. Natural ventilation depends on factors like wind speed, temperature variations, and atmospheric pressure, all of which can fluctuate significantly. These variations can affect the amount of air entering and circulating through the mine. For example, a sudden change in weather could result in reduced airflow, which might compromise the air quality and overall safety of the underground environment. This unpredictability can pose challenges in maintaining a consistently safe atmosphere for workers, making it essential to have a backup or supplementary ventilation system for more controlled airflow.

In contrast, the other options highlight aspects of natural ventilation that are generally considered advantages, such as cost-effectiveness and the potential for enhancing air quality, but do not address the inconsistency inherent in relying solely on this method.