Airports are major business sites with many employees in addition to passengers visiting on a daily basis. Despite aircraft movements being a highly visible part of airport life, local air quality often is more impacted by ground-based emissions from cars, trucks and busses than the emissions of aircraft.
Around airports, the chemical emissions that cause the greatest concern include; nitrogen oxides (NOx), volatile organic compounds (VOCs), carbon monoxide (CO) and particulate matter (PM). The impact of other trace emissions, such as sulphur dioxide (SO2), hydroxyl radicals, nitrous and nitric acids, still requires better understanding, but it is currently believed to be negligible.
Cleaner aircraft technology
Since the 1960’s, technical developments mean today’s new aircraft emit 50% less carbon monoxide and 90% less smoke and unburned hydrocarbons than those made 50 years ago. Nitrogen oxide (NOx) levels have also been cut, and modern aircraft now emit 40% less nitrogen oxide than in 1981. As a result of these technological improvements, aircraft can often have less impact on local air quality around airports than road traffic: in some cases, 95% of the local particulate matter comes from cars, trucks and other ground vehicles, rather than aircraft. The International Civil Aviation Organization (ICAO) sets standards for nitrogen oxide emissions and regularly tightens these for each new generation of aircraft. However, there is still more to be done, and the industry has a number of projects underway to reduce its effects around airports further.
Limiting the impact at airports
Aircraft emissions are reduced further when airports provide fixed electrical ground power and pre-conditioned air supplies at the terminal gates. These enable aircraft to switch off their auxiliary power units at terminal gates, reducing fuel burn and pollutants. Taxiing and holding times may be reduced by creating more direct taxiways and holding aircraft at the gate until departure slots are confirmed, generally reducing congestion.
Other sources of emissions that affect local air quality around airports include power plants, ground service equipment and vehicles. Mitigation measures taken by airports and their partners include modernising power plants, ground equipment and vehicle fleets. Diesel and petrol vehicles are being replaced at many airports with those using alternative fuels such as liquid petroleum gas, compressed natural gas, hydrogen, electricity and even compressed air!
Many airports are working with the local authorities to introduce measures to reduce road traffic, improve ground traffic flow and encourage cleaner, greener methods of transport to and from the airport. Airports work with local road and transit authorities to help develop roads and public transport including rail, trams and buses.
Outlook
In the meantime, the aircraft and engine manufactures are introducing further targets to reduce aircraft emissions, including an additional 80% cut in nitrogen oxide by 2020. Airports are also working with the aircraft and engine manufacturers to further reduce emissions and noise impact on local communities. In addition, the efficiency targets to reduce fuel consumption and cut emissions of greenhouse gases will lead to a further reduction in pollutants such as nitrogen oxide and carbon monoxide.