Factbox: What deal on CO2 standards means for Airbus, Boeing jets

(Reuters) - Global aviation leaders agreed on Monday to the world's first carbon dioxide emissions standards for new and existing plane programs starting in 2020, three sources familiar with the matter said. Experts at the International Civil Aviation Organization (ICAO) had been poring over a set of "stringency options" ranging from 1 to 10. These would curb CO2 emissions from large jetliners from 20 percent in the case of option 1 to 40.4 percent in the case of the toughest standard, option 10. While most nations favored a high standard for future aircraft that have yet to be designed, the most contentious issue revolved around which option to choose for aircraft already in production, with an impact for the world's two largest planemakers Airbus and Boeing . They settled on option 7, the sources said, backing a proposal from the United States that had been opposed by some European nations who favored option 6. The standards must still be approved by the UN aviation agency's governing council. (Reporting by Allison Lampert, Tim Hepher; Editing by Cynthia Osterman)