What can be a consequence of insufficient ventilation in a building?

Insufficient ventilation in a building can lead to an accumulation of indoor air pollutants, which is a significant concern for both health and comfort. When there is inadequate airflow, contaminants such as volatile organic compounds (VOCs), dust, mold spores, and carbon dioxide can build up. This can result in a decline in indoor air quality, potentially causing health issues for the occupants, including respiratory problems, headaches, and fatigue.

Proper ventilation is essential for diluting and removing these pollutants, as well as for maintaining a fresh and healthy indoor environment. In contrast, the other options do not reflect the realities of insufficient ventilation, as it typically causes higher energy costs, worsened air quality, and potential increases in humidity levels rather than lowering them.