Like many industries, the emissions from aircraft and other activities at airports can have an effect on the local air quality in the nearby areas.
In the immediate vicinity of airports, emissions of nitrogen oxides (NOx), volatile organic compounds (VOCs), carbon monoxide (CO) and particulate matter (PM) are usually considered the most important contributors to local air quality concerns. The contribution of other trace emissions such as sulphur dioxide (SO2), hydroxyl radicals, nitrous and nitric acids, still requires better understanding but is currently believed to be negligible.
Technical developments since the 1960s mean today’s new aircraft emit 50% less carbon monoxide and 90% less smoke and unburned hydrocarbons than those made 50 years ago.
Oxides of Nitrogen (NOx) levels have also been cut, and modern aircraft now emit 40% less NOx than in 1981. As a result of these technology improvements, aircraft can often have a smaller impact on the local air quality around airports than road traffic. The International Civil Aviation Organization (ICAO) sets standards for NOx emissions and regularly tightens these for each new generation of aircraft. However, there is still work to be done and the industry has a number of projects underway to further reduce its effects around airports.
Limiting the impact
Aircraft emissions can be further reduced when airports provide fixed electrical ground power and pre-conditioned air supplies at the terminal gates. These allow aircraft to switch off their auxiliary power units at terminal gates, reducing fuel burn and pollutants. Reducing taxiing and holding times may be achieved by construction of more direct taxiways, holding aircraft at the gate until departure slots are ready and the relief of congestion in general.
Other airports sources of emissions that affect local air quality include power plants, ground service equipment and by airside and landside vehicle fleets. Mitigation measures taken by airports and their partners include modernising power plants, ground equipment and vehicle fleets. Diesel and gasoline vehicles are being replaced with those using alternative fuels such as liquid petroleum gas, compressed natural gas, hydrogen, electricity and even compressed air. Airports usually need to build new infrastructure to provide these alternative fuels.
Many airports, in cooperation with the local authorities have introduced measures to reduce road traffic, improve ground traffic flow and encourage less polluting methods of transport to and from the airport. Airports need to work with local road and transit authorities to develop roads and public transport including light or heavy rail, trams and buses.
In the meantime, the aircraft and engine manufactures are continuing to target further aircraft emission reductions, including an additional 80% cut in NOx by 2020. Airports are working with the aircraft and engine manufacturers to further reduce emissions and noise impacts on local communities.
In addition, the gains in efficiency that the industry is targeting, in its move to reduce fuel consumption and cut the emission of greenhouse gases, will also lead to a further reduction in pollutants such as NOx and carbon monoxide.