This is the cure for dirty sock syndrome. Air ducts are often the source of odours, caused by smoke, pets, cooking, spoilage, and other agents. FreshDuct Odour Eliminator is specially formulated to control odours gently, but effectively. If you have an odour from mould in air handlers, ductwork, or coils, then this is a great product for you. Its non-toxic, biodegradable formula encapsulates and destroys odour-causing molecules on contact, while time releasing a fresh fragrance - freshening and deodorizing the interiors of both, lined and unlined ducts.