Air Quality

Air pollution is one of Europe’s largest environmental risks, with impacts on health and wellbeing as well as premature death, mostly related to cardiovascular and respiratory diseases and lung cancer. There is also increasing evidence of additional impacts, such as mental health and diabetes. The EU Ambient Air Quality Directives

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contain regulatory limits for various pollutants, including amongst others, particulate matter (PM₁₀ and PM_2.5), nitrogen dioxide (NO_²), ozone (O₃), heavy metals and sulphur dioxide (SO_²). By the end of 2024, a revised EU Ambient Air Quality Directive is due to be adopted and will set 2030 EU air quality standards aligned more closely with the 2021 World Health Organization recommendations in order to mitigate air quality impacts on health

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Estimates show that in 2022, 96% of the EU’s urban population was exposed to concentrations of fine Particulate Matter (PM_2.5) above the WHO guideline level for mean annual concentration of 5µg/m³. Moving close to the WHO guideline values would significantly reduce the current number of estimated premature deaths in the EU attributable to PM_2.5 (253 000), NO₂ (52 000) and O₃ (22 000) during 2021

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. National Air Pollution Control Programmes set out how Member States intend to achieve emission reduction commitments

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Aviation’s Contribution to Air Pollution

While a main source of air pollution in the vicinity of airports originates from aircraft operations, air quality is also impacted by ground support equipment, surface access road transport and airport on-site energy generation.

Aircraft engines produce similar emissions to other sources of fossil fuel combustion with the most significant from an air quality perspective being nitrogen oxides (NO_X)⁷ particulate matter, volatile organic compounds (VOCs), sulphur dioxide (SO₂) and carbon monoxide (CO). Studies also reported that aircraft emissions can contribute to elevated ozone (O₃) levels

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Furthermore, aircraft engines emit ultrafine particles (UFP) under a wide range of operating modes, which is a subset of particulate matter smaller than 100 nanometres in size (PM_0.1). Studies show health impacts on respiratory and cardiovascular systems, as well as long-term effects on premature deaths, from exposure to UFP that can enter the bloodstream and act as carriers of toxic substances

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New engine technology developments, such as lean-burn combustors, are mitigating particulate matter emissions at source. The development of cleaner fuels (lower volatile organic compounds and sulphur content) through hydrotreatment of fossil fuels and use of sustainable aviation fuels can also reduce particulate matter emissions and thereby reduce air quality impacts

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. However, aviation’s contribution to air pollution will remain a challenge in the future (see Sector Overview chapter).

Impacts on Local Air Quality

Currently, applicable EU Ambient Air Quality Directives do not require mandatory air quality measurements near airports, as air quality must be measured where the levels of pollutants are representative of the general population’s exposure, normally in nearby residential areas.

A recent study

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modelled the atmospheric concentrations of air pollutants in 2018 for six cities in Europe with large airports (Paris Charles de Gaulle, Amsterdam Schiphol, Frankfurt am Main, Munich, Brussels Zaventem and London Heathrow). The results from the simulations showed that the contribution from aviation on the average annual concentrations in the respective city centres was 2.5% for NO₂, 1.8% for SO₂, 0.5% for PM₁₀ and 0.3% for PM_2.5, whereas the average contribution at the airport location was 38% for NO₂, 45% for SO₂, 6.0% for PM₁₀ and 4.5% for PM_2.5.

Exposure to high NO₂ from aviation could be significant in residential areas around airports. While the NO₂ contribution from aircraft at one airport location was 55%, which represented a concentration of 17μg/m³ against a WHO guideline value for mean annual concentration of 10 μg/m³, the relative contribution of aircraft declines as a function of distance from the airport with a reduction rate of 63% for every 2.8 km separation from the airport. The declining trend as function of distance is also a result of a larger contribution from other sources in the city of (e.g., road transport and residential combustion) thereby reducing the relative contribution from aviation.

Following a request for information to the European Environment Information and Observation Network (Eionet), several studies were received from EU Member States measuring air quality around the airports of Vienna, Brussels, Copenhagen, Paris-Charles de Gaulle, Nantes, Bordeaux, Lille and Helsinki

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. All studies included UFP as a focus of concern around airport and some covered legislated pollutants (NO₂ and PM₁₀).

For UFP, high Particle Number Concentration (PNC) can be considered above 10 000 particles/cm³ (24-hour mean) or 20 000 particles/cm³ (1-hour). High PNC in air were registered under conditions of unfavorable atmospheric dispersion with direct inflow from the airport in most cases. A correlation between the UFP concentration in the surrounding area of the airport and the number of flight movement was also seen. This relationship was not so clear for nitrogen oxides and particulate matter as contributions from other sources such as road traffic could also be significant. These studies also noted the reduction in UFP concentration with increasing distance from the airport.

illustrates these changes in relation to distance from Paris Charles de Gaulle airport

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, where airport activities are estimated to be the main source of UFP within a distance of 5 km from the airport.

There are some constraints, however, when comparing UFP studies which often use different methodologies, particle size ranges and monitoring time periods. Air quality levels are also highly influenced by meteorology and sampling points must be located downwind of the airport to properly monitor their impact on air quality levels in the surrounding areas.

While there are no guideline levels set for UFP by WHO, they have provided good practices for the management of UFP

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. Furthermore, the revision of the Ambient Air Quality Directive

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considers airports as possible air quality hotspots, defined as locations within a zone in which the population is likely to be directly or indirectly exposed for a period which is significant in relation to the averaging period of the air quality standard. Airports are also identified as one of the locations where UFP should be measured to ensure that adequate information is available.

⁷Nitrogen Oxides (NOX) are a combination of Nitric Oxide (NO) and Nitrogen Dioxide (NO2).

Published in collaboration with