In order to promote the use of human and nature-friendly bicycles, the United Nations declared 3 June as World Cycling Day with a decision taken in April 2018.
When calculated according to the passenger capacities of the vehicles, a passenger emits an average of 16 grams of carbon dioxide per kilometer by bicycle, 72 grams by motorcycle, 55 grams by automobile, 68 grams by bus and 285 grams by plane.