What is a foul odor?

A foul odor is an unpleasant, offensive, or disgusting smell. It can be caused by a variety of things, including bacteria, mold, sewage, and chemicals. Foul odors can be a nuisance, and they can also be a health hazard. Some foul odors can cause nausea, vomiting, and headaches. In some cases, foul odors can even be fatal.