Cruise ship pollution in Europe is a major part of the environmental impact of shipping. Most cruise ship companies operating in European exclusive economic zones (EEZs) are part of two megacorporations: Carnival Corporation & plc and the Royal Caribbean Group. In 2017, Carnival's cruise ships alone caused ten times more sulphur oxide (SOx) air pollution than all of Europe's cars (over 260 million) combined, as the ship fuel emits about 2,000 times more sulphur oxides than normal diesel fuel. All cruise ships together also accounted for 15% of the nitrogen oxide (NOx) particles emitted by all of Europe's passenger vehicles, and released large amounts of carbon dioxide (CO2), phosphorus (P4), soot, heavy metals and other particulates into the atmosphere as well.