Aviation and Air Pollution - a Quick Guide to the General Issues

Polluted air is a public health hazard that cannot be evaded. It is widely known that long-term exposure to air pollution enhances the risks of cardiovascular and respiratory diseases. Scientists from the Max Planck Institute for Chemistry and the University Medical Center Mainz now calculated in a new study that the global, public loss of life expectancy caused by air pollution is higher than many other risk factors such as smoking, infectious diseases or violence.

Aviation significantly contributes to this pollution. New Scientific research shows that this contribution to overall pollution levels occurs at a global level and is not just restricted to those areas closest to airports. However, areas close to airports (within 6 miles) suffer the worst effects and often include high density urban populations.

Environmental Protection UK believes that no developments or alterations to the UK aviation infrastructure, air operations or flight scheduling should result in a breach of the EU limit values or UK air quality objectives, or worsen current breaches. Emissions considered must include direct emissions from aircraft, air-side service vehicles and plant, and the surface access required for airports.

The LBA application sets out evidence that it believes meets these above requirements.


Environmental Protection UK is concerned at the potential impact of the apparent ‘predict and provide’ approach that is being taken to air travel in the UK .

We would like to see aviation policies developed in a way which is consistent with the approach used for other transport sectors, and aviation should be fully bedded into an integrated transport policy, rather than being treated as a separate issue.

Air pollutant emissions from aircraft have been subjected to less rigorous control than road traffic emissions, and the rapid growth of global aviation is a matter of concern in relation to human exposures to pollutants, and consequent effects upon health.

There is lots of information from many different sources into the types of pollutants that are emitted directly by aircraft and by airport activity.

While most of the gas phase content of typical airliner engine exhaust consists of N2, O2, CO2, and H2O, many residual products are also jointly released in the atmosphere, including NOx, CO, SO2, a large number of hydrocarbons and aerosol particles containing organic and inorganic components having non-volatile and semi-volatile properties (Masiol and Harrison 2014). As from other combustion sources, the list of such products may also include compounds with known or suspected adverse effects on human health.

even the high altitude emissions can impact on air quality in the atmospheric boundary layer where people live and breathe (e.g., Barrett et al 2010). Therefore, impacts of aviation upon air quality and the assessment of related health effects are major questions currently addressed in scientific research and debated by policy-makers and stakeholders.

Airports and aviation generate air pollution through a range of sources: • Combustion of aviation fuel – which is mostly composed of kerosene - produces nitrogen oxides (NOx), carbon monoxide (CO), sulphur oxides (SOx), hydrocarbons and particulates.

  • As engines are working inefficiently on approach (as they only use about 30% of the available power) a certain amount of unburnt kerosene is released. These unburnt fuel droplets are a source of volatile organic compounds (VOCs)

  • As aircraft tyres get worn and burnt during take-off and (especially) landing, they release particulate matter (PM).

Aviation and air pollution

Air quality in the vicinity of airports is not just influenced by the emissions from aircraft engines, but also from other sources such as ground operations, surface access road transport and airport on-site energy generation and heating [90]. The most significant emissions related to health impacts from aviation activities are particulate matter (PM), nitrogen oxides (NOX) and volatile organic compounds (VOCs). Some of these primary pollutants undergo chemical and physical transformations in the atmosphere that in turn produce other pollutants such as secondary particulate matter21 and ground-level ozone.

Nitrogen oxides (NOX)

NOX emissions are primarily produced by the combustion of fossil fuels, especially at high temperatures such as those experienced in aircraft engine combustors. In the atmosphere, nitrogen monoxide (NO) is rapidly oxidised to nitrogen dioxide (NO2), which is associated with adverse effects on human health such as lung inflammation. NO2 also plays a key role in the formation of secondary particles and ground-level ozone. Thus, nitrogen oxides have both a direct and an indirect impact on air quality.

Particulate matter (PM)

Particulate matter is a general term used to describe very small solid or liquid particles. Emissions from aviation related activities, in a similar manner to other sources using carbon-based fuels, contain PM10 and PM2.5 emissions22, as well as ultrafine particles (PM1, PM0.1) that have very small diameters [91]. Such small particles, irrespective of the combustion source, can deposit in the human lung, pass natural barriers in human cells and enter the bloodstream. Solid ultrafine particles can trigger inflammation and act as carriers for toxic substances that damage the genetic information in cells. The EU Ambient Air Quality Directives [14] contain regulatory limits for PM10 and PM2.5 in ambient air, but not for ultrafine particles. However, PM2.5 is considered to be a good indicator of general risk associated with exposure to particulate matter. As the mass of the ultrafine particle emissions is so low, measurements of aircraft engine emissions have also focused on the number of emitted particles.


The presence of ozone in the high-altitude stratosphere provides an essential natural shield against harmful ultraviolet radiation from the sun. However, ground-level ozone can cause several respiratory problems, including reduced lung function, bronchitis, emphysema and asthma.

Whilst the LBA planning application sets out to meet the criteria set out by current European legislation this does not cover every pollutant associated with aeroplane emissions.

For example:

Volatile organic compounds (VOCs), hydrocarbons VOCs include a wide range of organic chemicals such as hydrocarbons (e.g. methane, benzene, toluene), halocarbons and oxygenates. VOCs have no colour, smell or taste, and they easily vaporize at room temperature. Hydrocarbons can be hazardous to human health even at low levels, particularly if the exposure is long term. For instance, long-term exposure to benzene has been linked to an increased incidence of anemia and leukemia; toluene can affect the central nervous system; and moderate levels of formaldehyde can lead to irritation of the eyes, nose and upper respiratory track. Some VOCs can cause cancer.

VOCs are not specifically mentioned in the LBA application documents on air quality.

The legislation relating to VOCs is unclear.

It is widely recognised that legislation needs to be under constant review and regulatory frameworks need to be updated to respond to the findings of scientific research in relation to air pollution and the specific contribution of aviation to this.

Whilst technologies that improve the emissions of some know pollutants have been developed, the process of introducing them is slow and complicated. For example, some technologies that reduce the emissions of Nitrogen oxides also reduce the energy efficiency of engines and therefore result in higher emissions of carbon.

Further, the scientific community has recognised that there is a specific problem within the aviation industry centered around its constant drive for growth.

Increases in the number and size of airports will directly undermine technological innovation and changes in regulatory frameworks that look to reduce emissions of harmful pollutants.

Jenny Bates, a campaigner at Friends of the Earth, suggested government could reduce the atmospheric impacts of the aviation sector by cancelling airport expansion plans. She said:

‘Climate breakdown and air pollution are both crises that are costing lives. Aviation is an important contributor to both of these so it’s essential that the number of planes in the sky is cut down. This means putting an end to the expansion plans of airports across the country.

© 2020 by Group for Action on Leeds Bradford Airport (GALBA)