Black mucus is rare. It can be the sign of a fungal infection, or exposure to pollutants such as coal, dust or cigarette ...

Snot is made up of water, proteins, antibodies, and dissolved salts, explains Jonathan Parsons, M.D., a professor in the Department of Internal Medicine at The Ohio State University Wexner Medical ...

Mucus is a normal part of the lungs. But smoking and other issues can cause too much mucus to collect there. (Photo Credit: iStock/Getty Images) Your body makes about a liter (approximately 1 quart) ...