According to a study by the environmental non-governmental organisation (NGO) Greenpeace, the route between Lisbon and Tires - the shortest in the country - rose one position, from 2021 to 2022, in the carbon intensity table by registering emissions of 108.68 kilos of carbon dioxide (CO2) per kilometre, with a total of 118 private jet flights travelling the 20.37 kilometre distance between the capital airport and the airfield on the outskirts of Lisbon.

At the top of the carbon intensity table, which analyses routes with more than ten flights per year, is the route between Farnborough and Blackbushe, in the United Kingdom, with 13 flights registered in 2022 to cover 7.41 kilometres and which produced 240.23 kilos of CO2 per kilometre.