The Effects of Airport
Congestion on Air Pollution
It's no secret that aircraft operations are a significant contributor to carbon emissions and air pollution, specifically the air pollution found around major airports. Aircraft engines release many different types of byproducts into the surrounding air including carbon dioxide, nitrogen oxides, carbon monoxide, sulfur oxides, and hydrocarbons (from fuel) that are unburned or partially combusted, particulates, and other trace compounds (Schlenker & Walker, 2011).
Sources of Aviation Air Pollution
When we think of aircraft operations, typically what comes to mind is takeoff, landing, and flying at cruise altitude from one location to another. There is, however, another aspect of aircraft contributing to air pollution that some may not consider: aircraft operations on the ground. This includes taxiing to or from the terminal gate, Auxiliary Power Unit operation while parked, and even ground support equipment operation (airfield vehicles, aircraft tow tractors, baggage vehicles, etc.). Although they seem insignificant, these contributing sources are, in fact, very important when you consider their impact on pollution directly surrounding airports. In 2014 an air quality study performed by the University of Southern California's Keck School of Medicine found that pollution from aircraft at Los Angeles International Airport was affecting the airports surrounding neighborhoods more than had been previously believed (Peterson, 2014).
Aviation Air Pollution Quick Facts
- Aircraft engine idling produces more CO and NO emissions per minute than any other stage of flight
- Aircraft engine emissions are higher during low power when the engine is less efficient
- Average taxi time from gate to runway increased by 23% from 1995 to 2007
(Schlenker & Walker, 2011)
The following graphic shows the breakdown of emissions contributions at Frankfurt International Airport in 2005. As the data is old and improvements have been made since this time, the charts are shown here only to put into perspective the proportions of emissions each category contributes.
(Zaporozhets & Synylo, 2020)
What does this mean?
Simply put, congestion at airports directly impacts the emissions output of aircraft, and therefore overall air pollution, at a given airport. In 2011, Schlenker and Walker even found that airport delays on the east coast of the United States led to more airfield congestion at LAX, which directly impacts air pollution levels around the Los Angeles area.
Ways to Reduce Airport Air Pollution
- Halt the use of Auxiliary Power Units at terminal gates and instead use ground power and externally supplied air conditioning
- Reduce taxi times by keeping aircraft at the gate until its departure slot is confirmed
- More Direct taxi routes that would limit idle power time of engines
- Taxi procedures that limit aircraft to one engine when safe and practical
- Use of electric, natural gas, hydrogen, or compressed air ground-support vehicles
- Use of efficient tow tractors to move aircraft from gate to runway without using aircraft engines
- Assigning aircraft to the closest open gate from the runway to lower taxi time
- Optimizing arrival and departures when external delays may increase congestion
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References
Improving air quality. (n.d.). Aviation Benefits Beyond Borders. https://aviationbenefits.org/environmental-efficiency/improving-air-quality/
Peterson, M. (2014, May 30). Air pollution from LAX jets worse than previously known, says USC study. KPCC - NPR News for Southern California - 89.3 FM. https://www.kpcc.org/2014-05-29/air-pollution-from-lax-jets-worse-than-previously
Schlenker, W., & Walker, W. (2011, November). AIRPORTS, AIR POLLUTION, AND CONTEMPORANEOUS HEALTH. National Bureau of Economic Research. https://www.nber.org/system/files/working_papers/w17684/w17684.pdf
Zaporozhets, O., & Synylo, K. (2020). Modeling of Air Pollution at Airports. Environmental Impact of Aviation and Sustainable Solutions. https://doi.org/10.5772/intechopen.84172
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