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The environmental effects of peak hour air traffic congestion: The case of London Heathrow Airport
Abstract
The commercial air transport sector currently faces the serious and seemingly incompatible challenge of meeting growing consumer demand for flight whilst reducing its environmental impact and meeting increasingly stringent international emissions targets. Growing demand for air travel combined with improvements in environmental performance in other industrial sectors means that commercial aviation has become a key focus for tackling climate change. The aim of this paper is to quantify the impacts of capacity-induced airport congestion using the case of London Heathrow Airport. The paper quantifies the environmental effect of airborne delays to inbound aircraft at the heavily constrained London Heathrow Airport on emissions and local air quality. The findings reveal that the additional CO2 and NOx emissions resulting from airborne delays are significant and will increase if capacity constraints on the ground are not addressed. The results are analysed in the context of Heathrow's climate change targets and current debates surrounding expansion and the challenge of reconciling environmental sustainability with aviation growth.
... In the literature, the issue of CO 2 emissions, which has the highest share in air pollution caused by aviation, is examined in detail. In addition to the air pollution caused by aviation activities in the general environment, the effects on the air of the residential areas around the airports are also the basis of research (Irvine et al., 2016). ...
... In order to control the emissions that cause climate change, limits and future reduction targets are set by some airports. In this context, managing the traffic effectively has gained importance in airports (Irvine et al., 2016). ...
Demand for air transport is increasing steadily with technological advances and the increase in the global trade. Parallelly, there is an ambition for continuous growth and increase of infrastructure capacity by aviation companies, government agencies, and business circles. The understanding of sustainability, which takes into account the environmental and social impacts as well as economic concerns for businesses, is becoming widespread. The airline transportation industry is one of the sectors that come to the fore due to the magnitude of its environmental impacts. Airports, on the other hand, are an important focal point to examine sustainability impacts, especially air pollution and noise, due to landing and takeoff and many activities taking place in between. In this study, a new set of airport sustainability indices is developed by using extant research and expert opinion.
... It can cause flight delays and cancellations, leading to lost productivity, missed connections, and increased costs for airlines and passengers [2][3][4][5]. It can also increase fuel consumption and emissions, contributing to climate change and air pollution [6,7]. Additionally, air traffic congestion can affect other industries that rely on air transportation, such as tourism and international trade. ...
The demand for air transportation increases significantly worldwide, and the number of aircraft and passengers is also rising. This situation directly affects the major airports and their surrounding Terminal Manoeuvring Areas (TMAs) because they launch new destinations and increase flight frequency. However, airport and airspace structures have some difficulty meeting this increasing demand. Therefore, there is an increase in airborne delay in air traffic congestion. Airborne delay severely affects TMAs operations since they have several entry points, yet all arrival traffic lands mainly at the same airport. This problem also expands the flight duration within TMAs. Air traffic controllers regulate the arrival traffic with separation and sequencing methods, including vectoring, point merge approach or holding manoeuvres. These are generally implemented at a constant flight level. Therefore, they generate level-off flight segments during the descending profile of arrival aircraft. The level-off segments directly increase the fuel consumption and emissions values because of engine configurations. Therefore, this study aims to expose the level-off segments for the London Heathrow, Amsterdam Schiphol, Paris Charles de Gaulle and Istanbul airports. The results show that Amsterdam Schiphol has the lowest level-off time to total descent time ratio of 12.8% among other airports.
... The terminal manoeuvring area (TMA) is where many of the environmental impact of aviation oc-39 curs. As an example, [5] investigated the environmental impact of air traffic congestion during peak 40 hours at London Heathrow Airport, highlighting the contribution of holdings. More recently, [2] 41 expanded upon this insight, examining environmental inefficiencies in arrival procedures and em-42 phasised the detrimental environmental impact of holdings compared to other procedures. ...
This paper introduces a data-driven technique for labelling airborne holdings based on their underlying causes, specifically distinguishing between adverse weather conditions and other causes, such as airport capacity. Utilising a dataset comprised of flight trajectories arriving at 45 European airports over a nine-month period, extracted from automatic dependent surveillance-broadcast data, this paper provides valuable insights into the causes behind airborne holdings and their relative environmental impact. The proposed approach involves employing an existing neural network to identify airborne holdings. Subsequently, these holdings are cross-referenced with actual weather observations obtained from meteorological aerodrome reports. Following this, a subset of the holdings is labelled as either weather-related or attributed to other causes, based on historical air traffic flow management regulations. Finally, the cause of the majority of unlabelled holdings is determined using semi-supervised learning. The findings indicate that at least one-quarter of the 30-minute time periods with airborne holdings identified by the neural network can be attributed to weather-related factors, with reduced visibility, strong winds, and convective weather, emerging as the primary contributing events. Intriguingly, weather-related causes account for approximately 40% of the total fuel consumption associated with these procedures.
... Additionally, taking London Heathrow Airport as an example, Irvine et al. (2016) quantify the environmental effect of airborne delays to inbound aircraft at the heavily constrained London Heathrow Airport on emissions and local air quality [29]. Therefore, resolving airspace congestion, improving runway operations, and enhancing cooperative release mechanisms can improve OTP. ...
Air transportation, which is a derived demand, is booming following the rapid development of the world economy, and carbon emissions from the air transportation industry, which takes fossil fuels as its main energy source, have been increasing. Therefore, with global warming attracting considerable attention, the issue of how to reduce carbon emissions from air transportation has become a hot issue. We take China Eastern Airlines Corporation Limited (China Eastern) as an example to analyze the main factors influencing airlines’ carbon emissions, specifically around the impact of airline internal operating indicators, such as available seat kilometers (ASK), passenger load factor (PLF), fuel consumption per unit passenger kilometer, the average age of operated aircraft, on-time performance (OTP), etc. This paper uses a correlation analysis, panel regression analysis, and other ways to explore the influence mechanism of the above factors on carbon emission intensity. The conclusions for China Eastern are the following: first, PLF has a significant negative relationship with carbon emission intensity; second, fuel consumption per passenger kilometer has a significant negative relationship with carbon emission intensity. Third, OTP has a significant positive relationship with carbon emission intensity. Fourth, fleet size has a significant positive relationship with carbon emission intensity. Finally, we propose several targeted carbon abatement measures for China Eastern, such as improving PLF and OTP, reducing fuel consumption per unit passenger kilometer, speeding up fleet renewal, etc.
... Total emissions for each of these pollutants are seen fluctuated throughout the month. We are using the emission index for HC, CO, and NO x based on what has been used by other studies [21][22][23] and assumed that the values of fuel flow and emission index are identical for the same aircraft model such as B737-200, B737-300 was assumed to have the same FF and EI. ...
Aircraft engines release greenhouse gases that are comparable to those emitted from the combustion of fossil fuels, raising significant environmental concerns regarding their global and ground-level air quality impacts. With the escalating demand for air transport worldwide, air traffic has resulted in various issues and consequences for the global and national environments. The International Civil Aviation Organization (ICAO) has identified several pollutants in their database, including hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxides (NOX). To estimate the gas emissions from aircraft engines, this study focused on gathering and analyzing aircraft movement data within the Kuala Lumpur Flight Information Regions (KLFIR) of Peninsular Malaysia, specifically limiting the analysis to the northern region. To accomplish this, a web-based application was developed, and a data mining approach was employed. The methodology comprised data collection and optimization, pre-processing and post-processing, database design, web application data analysis, and engine gas emission calculation, following the framework established by a prior study. The data utilized for this study were collected from existing equipment in the laboratory and obtained from freely available online services, specifically focusing on the year 2019. Through the data mining approach using ADS-B data, the analysis successfully estimated aircraft emissions, with nitrogen oxides (NOx) accounting for the highest emission count at 82% of the total, while carbon monoxide (CO) and hydrocarbon (HC) emissions were the lowest at 13 and 15%, respectively.
... Other TMA studies, like [14], focus on flight time as the criterion to assess vertical efficiency in descent procedures. At the TMA level, [15] addresses the environmental impacts due to congestion, and [16] discusses various operational and fuel inefficiencies for different airports. Point-merge has been designed with operational performance in mind. ...
In this paper, we analyze two months of trajectory data for aircraft landing in five major European airports. Based on open ADS-B data from the OpenSky Network and open performance models, we enrich all trajectories with automatically detected procedure information, fuel consumption, and emissions for supported aircraft types. To assess the inefficiencies associated with holding patterns, point merges, and continuous descent operations across different airports, we propose methodologies to quantify and compare these environmental inefficiencies. Holding patterns are found to have a higher negative impact on the environment than point merge and continuous descent operations. Furthermore, the paper provides recommendations for procedure evaluations of future airports, which could help policymakers and relevant stakeholders to evaluate the environmental performances of arrival procedures based on open data and open models.
... Airport congestion at busy airports increases taxiing times, causes delays in queuing and departure processes, and implies more fuel consumption, emission, and environmental impacts (Simic and Babic, 2015;Ashok et al., 2017;Cavusoglu and Macario, 2021). Irvine et al. (2016) discussed the impacts of air traffic congestion due to capacity constraints on the emissions produced. Ryerson et al. (2011) evidenced that the fuel consumed is much higher in congested airports. ...
Ground-level aircraft operations and landing and take-off cycle account for the vast majority of an airport’s total emission. Among other factors, planning skills are critical in minimizing the emissions produced and fuel burn through reducing taxi times during landing and take-off operations. This study examines the sustainable efficiencies of busiest European airports considering their success in reducing emissions during landing and take-off cycles and argues (i) emission per landing and take-off cycle is a good proxy for ground-level aircraft operation planning skills and provides more practical results than the total amount of annual emission, (ii) weight restriction procedure is necessary in Data Envelopment Analysis applications to ensure furnishing the impact of emission criteria on overall efficiency. A weight-restricted Data Envelopment Analysis model was constructed, and both physical and sustainable efficiencies of each airport were examined during nine years between 2010 and 2018. A combinative Analytic Hierarchy Process - Criteria Importance Through Intercriteria Correlation approach was used to define criteria weights, and a new modified approach was proposed and used to include these weights in Data Envelopment Analysis. Findings proved the necessity of weight restriction when one would examine the impact of emissions produced on sustainable airport efficiency. The Malmquist Productivity Index showed a great shift in physical output production; however, improvements to reduce landing and take-off cycle times have lagged behind the shift in physical output production.
... The Dutch government also issued a policy to provide incentives for private transport riders who can reduce the frequency of their travel during rush hours [4]. Congestion during peak hours impacts climate change and the sustainability of urban development due to pollution generated [5]. The capital of Asian countries is experiencing severe traffic congestion problems during work hours due to the number of private car users [6]. ...
... The LTO cycle is based on times in mode data during high activity periods at major airports for four modes of engine operation: taxi/idle, takeoff, climb-out, and approach [4]. LTO operations have a significant contribution (up to 70%) to an airport's pollutant emission inventory [3,27,28]. Other sources of emissions associated with aircraft movements considered in the study include the onboard auxiliary power units (APU) and aerospace ground support equipment (GSE). ...
In order to reduce the air pollution impacts by aircraft operations around airports, a fast and accurate prediction of air quality related to aircraft operations is an essential prerequisite. This article proposes a new framework with a combination of the standard assessment procedure and machine learning methods for fast and accurate prediction of air quality in airports. Instead of taking some specific pollutant as concerned metric, we introduce the air quality index (AQI) for the first time to evaluate the air quality in airports. Then, following the standard assessment procedure proposed by International Civil Aviation Organization (ICAO), the airports AQIs in different scenarios are classified with consideration of the airport configuration, actual flight operations, aircraft performance, and related meteorological data. Taking the AQI classification results as sample data, several popular supervised learning methods are investigated for accurately predicting air quality in airports. The numerical tests implicate that the accuracy rate of prediction could reach more than 95% with only 0.022 sec; the proposed framework and the results could be used as the foundation for improving air quality impacts around airports.
... Majority of them present case studies from different airports around the World and present the current challenges with the throughput from technical point of view. The analysis covers passenger throughput including building terminals and inside processes such as check-in, security, boarding, passport control, and so on; traffic and parking system; ground handling and airside throughput [1,2,3]; and environmental throughput [4,5,6,7]. These studies present the solutions to throughput problems of operating airports, examine various mathematical and statistical models for throughput forecasting; however, it is also crucial to investigate the estimated potential airport throughput when planning, building, and opening new airport. ...
From 2004 to 2013, a number of projects aimed at the development of transport infrastructure in Poland were completed. Some of them were aimed at supporting trans-European transport (TEN-T) network, as well as at increasing regional development by creating investment areas, growing life standards by better inhabitants’ mobility, decreasing unemployment rate, and so on. 81 projects were accomplished that were directly concerned with the development of airport infrastructure with financial support from European Union (EU).
In this paper, I aimed to describe the projects supporting the development of airports in Poland. I focused on the increasing passenger throughput that was assumed when applied for EU founds. This assumption was compared with current (2015) use of airports and the potential possibilities for increasing demand. Based on this hypothesis, herein the investments are presented.
As primeiras regulamentações ambientais em países desenvolvidos forçaram empresas a fazerem altos investimento medidas de proteção, porém quando esses custos começaram a ser repassados houve a confirmação de que havia o interesse público de pagar mais por um produto ou serviço com tal, assim os executivos começaram a testar estratégias de atração para esse setor, surgindo o termo pays-to-be-green. Com os investidores sendo atraídos por esses resultados econômicos-financeiros de empresas com responsabilidade social e financeira, surgiu então o termo Enrironmental, Social and Governance ESG, como um método para avaliação de empresas, a partir dos políticas e resultados dentro desses três pilares para a análise de ativos dentro das bolsas de valores. Como o ESG se demonstrou um meio para capitalização de recursos financeiros e Os aeroportos que são infraestruturas logísticas importantes, mas que possuem difícil capacidade de atingir retorno sobre o investimento e necessitarem de liquidez. Este estudo propõe investigar como as ações ESG, com os dados disponíveis para o cálculo de emissão direta de GEE para os aeroportos, poderá implicar no valor do patrimônio líquido das concessões. Foram utilizados como estudo de caso os aeroportos de Brasília (SBBR), Galeão (SBGL) e Campinas (SBKP). Por meio de um procedimento econométrico verificou-se por meio de uma regressão não-linear utilizando o método de Mínimos Quadrados Ordinários (MQO) quais são os coeficientes das variáveis econômicas, financeiras, de produção e ESG que podem estimar o valor do patrimônio líquido. Tais resultados também são comparados a análise de regressões feitas para ativos dos setores de energia, transportes e real estate. Os resultados obtidos sugerem que o coeficiente da variável de emissão direta de gases de efeito estufa é negativo para o atraçaõ de patrimônio líquido, o que em tese deveria acompanhar o resultado da movimentação de aeronaves que demonstrou sinal positivo. Este estudo provê evidências empíricas sobre a performance financeira de investimentos ambientais para o mercado brasileiro e aeroportos, sendo uma contribuição para a literatura.
Climate change mitigation calls for the limitation and reduction of greenhouse gas (GHG) emissions across all sectors. However, limiting GHG emissions from aviation has proven to be problematic for technical reasons (e.g., lack of low-carbon alternatives) as well as legal reasons (e.g., international aviation does not readily fall within any one state's jurisdiction). Relevant initiatives have followed two streams. At the international level, the International Civil Aviation Organization (ICAO) has adopted technical standards and, more recently, a market-based mechanism to limit emissions from international civil aviation. In parallel, states have adopted their own policies and measures to regulate emissions from both domestic and international aviation, ranging from tax and technical standards to traffic management and infrastructural development. While much of the literature on climate change mitigation in the aviation sector has focused on international efforts, this article reveals the importance of understanding the tensions and complementarities of the two streams.
This research summarises the aviation CO2 emissions studies that use the Intergovernmental Panel on Climate Change IS92 and Special Report on Emissions Scenarios storylines as GDP growth assumptions to estimate future global carbon dioxide emissions from the aviation sector. The inter-quartile mean and the first and third quartiles are calculated to enable researches studying climate change policies for aviation to use an average global baseline scenario with lower and upper boundaries. We also perform a simple meta-analysis to analyse the assumptions used to derive the baseline scenario and conclude, as expected, that change in revenue-tonne-kilometres and fuel-efficiency are the main drivers behind the baseline scenarios.
Purpose/approach
Despite the high profile of climate change rhetoric and the carbon intensive nature of flying, policies for controlling CO2 from aviation remain at odds with global commitments on climate change. Taking a carbon budgeting approach to compare future aviation scenarios with the scale of necessary emission reductions demonstrates the extent of this contradiction. The significant potential for ongoing aviation growth contrasts with the need to curb substantially global CO2 emissions across all sectors. For even a 50:50 chance of staying within the 2°C threshold, emission pathways imply around a 75% cut in absolute emissions by 2050 (from 1990 levels). Set against this, aviation’s CO2 emissions are expected to grow by between 170% and 480% over the same period, and they could feasibly be higher still.
Originality/findings
For the international community to be serious about its climate change commitments, moral and ethical concerns need to be considered alongside technical and economic issues. It is timely to question whether expansion of an industry with few technological options for decarbonisation is a reasonable way to gamble with our future.
Real time number concentrations and size distributions of ultrafine particles (UFPs, diameter <100 nm) and time integrated black carbon, PM2.5 mass, and chemical species were studied at the Los Angeles International Airport (LAX) and a background reference site. At LAX, data were collected at the blast fence (similar to 140 m from the takeoff position) and five downwind sites up to 600 m from the takeoff runway and upwind of the 405 freeway. Size distributions of UFPs collected at the blast fence site showed very high number concentrations, with the highest numbers found at a particle size of approximately 14 nm. The highest spikes in the time series profile of UFP number concentrations were correlated with individual aircraft takeoff. Measurements indicate a more than 100-fold difference in particle number concentrations between the highest spikes during takeoffs and the lowest concentrations when no takeoff is occurring. Total UFP counts exceeded 10(7) particles cm(-3) during some monitored takeoffs. Time averaged concentrations of PM2.5 mass and two carbonyl compounds, formaldehyde and acrolein, were statistically elevated at the airport site relative to a background reference site. Peaks of 15 nm particles, associated with aircraft takeoffs, that occurred at the blast fence were matched with peaks observed 600 m downwind, with time lags of less than 1 min. The results of this study demonstrate that commercial aircraft at LAX emit large quantities of UFP at the lower end of currently measurable particle size ranges. The observed highly elevated UFP concentrations downwind of LAX associated with aircraft takeoff activities have significant exposure and possible health implications.
The objective of this paper, which constitutes a part of the AERONOX project, is the investigation of the potential transformation of the active species emitted from aircraft into reservoir species. The analysis is based on modelling of transformations of the near-field region, 1 km behind a Boeing 767 and a Boeing 747 aircraft. The processes considered are, firstly the dynamics of the jet flow and the jet-wing tip vortices interaction and secondly the potential chemical transformations of species such as NO, NO2, HNO2, HNO3 and H2SO4. The wake dynamcal processes are performed by using the 3D turbulent Navier-Stokes equations. Chemistry is calculated using a box model including the photochemical and heterogeneous reactions. In the jet flow, calculations have been performed for two engines CFM 56 and RB 211. Temperature fields and dilution profiles are compared. In the wake, the influence of the vortical motion on the inboard and outboard jet engines is shown. The chemical calculations show that there is a rapid disappearance of OH and HO2 at the very beginning of the plume and simultaneous growth of HNO2 and HNO3. All the main chemical transformations are made in the hot jet flow. In the limits of the calculations, there is no significant chemical transformations during the first kilometre behind the Boeing 767, except for OH, HO2 and CH2H2 whose concentrations appear highly dependent on the local exhaust NOx concentration.
Worldwide increases in commercial air traffic have raised concerns about the effects of aircraft emissions on the atmosphere. The purpose of this study was to demonstrate the capability of a remote sensor, developed for the measurement of automobile emissions, in measuring nitric oxide emission indices from in-use aircraft on the ground without interfering with their normal operation. In two days of sampling at London Heathrow Airport, a total of 122 measurements were made of 90 different aircraft in a mix of idle, taxi-out, and takeoff modes. Aircraft measured at idle exhibited little nitric oxide emission. Emission indices measured from aircraft at higher thrust levels were not inconsistent with values from the ICAO Engine Exhaust Emissions Databank.
This paper presents a detailed estimation of fuel consumption and emissions during taxi operations using aircraft position data from actual operations at Dallas/Fort Worth International Airport. Making assumptions of the thrust level during each state, fuel flow and emission index values from International Civil Aviation Organization’s databank are extrapolated. This provides a relative comparison of all the taxi phases and their contribution to the total effect. Analysis reveals that stop-and-go situations, resulting primarily from congestion on airport’s taxiway system, account for approximately 18% of fuel consumed. The states of idling and taxiing at constant speed or braking were found to be the two largest sources of fuel burn and emissions, and the model estimates are sensitive to the thrust level assumptions for these states.Research highlights► Using detailed taxi data from DFW, we estimate fuel consumption and emissions. ► Stop-and-go situations constitute 18% of fuel consumed during taxi. ► Idling and taxiing at constant speed are the two largest sources of fuel burnt.
Aviation emissions contribute to the radiative forcing (RF) of climate. Of importance are emissions of carbon dioxide (CO2), nitrogen oxides (NOx), aerosols and their precursors (soot and sulphate), and increased cloudiness in the form of persistent linear contrails and induced-cirrus cloudiness. The recent
Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) quantified aviation’s RF contribution for 2005 based upon 2000 operations data. Aviation has grown strongly over the past years, despite world-changing events in the early 2000s; the average annual passenger traffic growth
rate was 5.3% yr-1 between 2000 and 2007, resulting in an increase of passenger traffic of 38%. Presented
here are updated values of aviation RF for 2005 based upon new operations data that show an increase in traffic of 22.5%, fuel use of 8.4% and total aviation RF of 14% (excluding induced-cirrus enhancement) over the period 2000–2005. The lack of physical process models and adequate observational data for aviationinduced cirrus effects limit confidence in quantifying their RF contribution. Total aviation RF (excluding induced cirrus) in 2005 was ~55mW m-2 (23–87mW m-2, 90% likelihood range), whichwas 3.5% (range 1.3–10%, 90% likelihood range) of total anthropogenic forcing. Including estimates for aviation-induced cirrus RF increases the total aviation RF in 2005–78 mW m-2 (38–139 mW m-2, 90% likelihood range),
which represents 4.9% of total anthropogenic forcing (2–14%, 90% likelihood range). Future scenarios of
aviation emissions for 2050 that are consistent with IPCC SRES A1 and B2 scenario assumptions have been
presented that show an increase of fuel usage by factors of 2.7–3.9 over 2000. Simplified calculations of total aviation RF in 2050 indicate increases by factors of 3.0–4.0 over the 2000 value, representing 4–4.7% of total RF (excluding induced cirrus). An examination of a range of future technological options shows that substantive reductions in aviation fuel usage are possible only with the introduction of radical technologies. Incorporation of aviation into an emissions trading system offers the potential for overall (i.e., beyond the aviation sector) CO2 emissions reductions. Proposals exist for introduction of such a system at a European level, but no agreement has been reached at a global level.
One of the main outcomes of open skies policies is the importance of service frequency in the competition between airlines. To keep load factors high while offering high frequency service, airlines tend to reduce the size of the aircraft used. On short-haul routes this phenomenon is even more apparent, especially on routes between hub airports, even though these routes and airports are often congested. This choice of service frequency and aircraft size must have important environmental consequences that this paper aims to evaluate and quantify. The analysis considers local air pollution, climate change and noise impacts and aims to evaluate whether the competitive environment that drives airlines to offer high frequency service carries an environmental penalty. The analysis showed that increasing aircraft size and adjusting the service frequency to offer similar seating capacity will increase local pollution but decrease climate change impact and noise pollution. When local pollution and climate change impacts are monetized and aggregated the analysis showed that environmental benefits will result from increasing aircraft size. But these benefits, in monetary terms, were found to be relatively small and sensitive to the assumptions made.
In the last decade, air traffic has increased dramatically with a significant increase in emissions. Our goal is to quantify the impact of aircraft emissions on regional air quality, especially in regards to PM2.5 and ozone. Here the focus is on Hartsfield–Jackson Atlanta International Airport which is the busiest airport in the world based on passenger traffic.First, aircraft PM2.5 emissions are estimated based on the Smoke Number (SN) by using the “first order” method. The Emissions and Dispersion Modeling System (EDMS) is used for gaseous species. PM2.5 emissions are estimated once based on the characteristic SN and a second time using the mode-specific SN. Further, aircraft emissions are processed in two ways: (1) allocating the emissions at the airport itself, and (2) by accounting for flight paths, mode, and plume rise.When the more conservative emission estimates are used (i.e, the characteristic SN estimates allocated to the airport), results suggest that Hartsfield–Jackson airport can have a maximum impact of 56 ppb on ozone with a 5 ppb average impact over most of the Atlanta area. PM2.5 impacts are also estimated to be quite large with a maximum local impact of 25 μg m−3. Impacts over most of the Atlanta area are less than 4 μg m−3. The second set of emissions with detailed spatial allocation leads to a less intense ozone impact with a maximum of 20 ppb and an average of less than 1 ppb. PM2.5 impacts, in this case, are about 1 μg m−3 within a radius of 16 km around the airport. The difference in these two results shows the importance of how aircraft emissions are treated. The impacts on ozone and PM2.5 of ground support equipment at the airport are smaller compared to the aircraft impacts, with a maximum impact of 2 ppb for ozone and 9 μg m−3 for PM2.5.
An air dispersion model, ADMS-Urban, was used to estimate temporal and spatial contributions to NOx concentrations from aircraft and traffic around Heathrow airport in West London. Special attention was devoted to the modelling of aircraft releases at different heights. Although emissions associated with traffic are smaller than those associated with aircraft, their impact at different locations around the airport, where people are exposed to air pollution, was found to be larger. It was also found that only the concentration levels on timescales of a few hours were relevant in terms of exposure. Integration of this kind of data may prove useful to identify more closely the likely exposure impacts to local populations caused by different pollution sources. In addition, a preliminary comparison of the results of the model with data available at a monitoring station nearby the airport was subsequently performed. Discrepancies between monitoring data and the model are discussed, suggesting that the aircraft contribution is overestimated and the traffic contribution underestimated.