Mucus, known by many as "snot," serves as a protective layer over the inner surfaces of the nose, sinuses, mouth, throat and lungs and is a means of flushing contaminants from the body. According to WebMD, mucus keeps membranes from drying out while trapping dust and other airborne debris before they lodge inside the sinuses or lungs. Mucus contains antibodies that destroy trapped bacteria and viruses.
Healthy people's bodies generate 1 to 1.5 liters of mucus every day, reports WebMD. Most people do not notice regular mucus production. However, when a person develops a cold or experiences an allergic reaction, his body's mucus production is likely to increase considerably. Some people experience an increased mucus flow when they drink milk as a result of allergies to lactose.
Discovery.com indicates that the body produces larger quantities of mucus when attempting to flush out bacteria or viruses. However, in some instances, it begins a vicious circle in which the more mucus that flows through the sinuses, the more the body produces additional mucus. While this is the body's way of clearing itself of invaders, it is not pleasant for the person experiencing it as he must continually blow his nose to avoid coughing.