Natural refrigerants are natural substances that serve as refrigerants in refrigeration systems (including refrigerators, HVAC, and air conditioning). They are alternatives to hydrofluorocarbon (HFC), hydrochlorofluorocarbon (HCFC) and chlorofluorocarbon (CFC) based refrigerants. Unlike other refrigerants, they are not synthetic chemicals and can sometimes be found in nature. They are not only used due to environmental sustainability as some applications are better suited to a particular natural refrigerant. Natural refrigerants are natural substances that serve as refrigerants in refrigeration systems (including refrigerators, HVAC, and air conditioning). They are alternatives to hydrofluorocarbon (HFC), hydrochlorofluorocarbon (HCFC) and chlorofluorocarbon (CFC) based refrigerants. Unlike other refrigerants, they are not synthetic chemicals and can sometimes be found in nature. They are not only used due to environmental sustainability as some applications are better suited to a particular natural refrigerant. HFC, HCFC, CFC classes of chemicals are all potent greenhouse gases. HCFC and CFC classes of chemicals are damaging to the ozone layer, with CFCs being a primary culprit. Natural refrigerants do not deplete the ozone layer and have a much lower impact on the environment. Though they may exist in nature, they are not entirely harmless or nontoxic but aside from ammonia are generally less harmful in the event of refrigerant release, although most are highly flammable.