Collective term for a series of totally fluorinated hydrocarbons (e.g., CF₄, C₂F₆), which are present in the atmosphere as a result of anthropogenic activities. These species are very resistive to destruction in the atmosphere and thus have extremely long lifetimes (thousands of years). As a consequence of their extremely long lifetimes and strong infrared absorption features, the large greenhouse warming potentials of these compounds is of some concern.