According to a study by Arpa Veneto (http://www.arpa.veneto.it/arpav/chi-e-arpav/file-e-allegati/dap-venezia/aria/Relazione_tecnica_emissioni_aeroportuali.pdf),
airports are responsible for the emission of pollutants produced by combustion activities: ozone (which is not directly emitted but generated by precursors’ emissions), carbon monoxide, nitrogen oxides, volatile organic compounds and particulate matter.
Nevertheless, the contribution of airports to the total volume of pollution is relatively marginal. In fact, a chapter dedicated to air transport in the Atmospheric Emission Inventory Guidebook by the EEA (European Environment Agency), contains some useful observations about airport-generated emissions. By way of example, it has been estimated that airport CO2 emissions are only circa 2% of the total amount of manmade emissions.
The following table has been taken from the European Environment Agency report on aviation dated July 2017; it outlines the contribution, based on various emissions, produced by air traffic to the total.
Generally, aircraft produce different pollutants during the various phases of a flight,.
Aircraft engines mainly emit nitrogen oxides (NOX), carbon monoxide (CO), volatile organic compounds (VOC), sulphur dioxide (SO2) and particulate matter (PM), in addition to carbon dioxide (CO2) and water (H2O) in the form of steam. Nitrogen oxide and particulate matter emissions are mainly produced during take-off and climbing phases, while carbon monoxide and hydrocarbons are mainly emitted during taxiing.
Moreover, releases on land are linked to airport operations: generators, auxiliary power units, ramp vehicles, engine tests, service vehicles, energy production plants, and work and maintenance equipment.
Moreover, these sources also include road traffic (personal vehicles, hired vehicles, taxis, buses, shuttle buses…) serving the airport and its users (passengers and personnel).
The entire aeronautical industry is relentlessly and formally committed to reducing emissions, particularly climate-changing emissions (CO2), primarily by following two specific programs in accordance with ICAO Resolution A39-3. These two programs are addressed, respectively, to airlines and aircraft manufacturers (CORSIA – Carbon Offsetting and Reduction Scheme for International Aviation) and to airports (ACA – Airport Carbon Accreditation).