Which of the following can be a consequence of foul odors in indoor environments?

Foul odors in indoor environments can lead to various negative health and psychological effects, with headaches and loss of appetite being common consequences. When individuals are exposed to unpleasant smells, it can trigger discomfort and even physiological reactions such as headaches. This is often due to the body's response to perceived harmful substances in the air, causing stress or anxiety that can further lead to nausea or a diminished desire to eat, ultimately affecting overall well-being.

In contrast, improved air quality, increased productivity, and enhanced mood are not typically associated with foul odors, as these factors usually arise in environments with clean, fresh air that promotes a sense of comfort and well-being.