Emissions of air transport

Summary memo to better understand the problems and issues

There is often confusion, when talking about emissions from aircraft, between low-level pollution around airports and high altitude greenhouse gas emissions. Simply put, there are some emissions below a level of 915 m (3,000 feet) and others above. Scientists agree pretty much on the fact that beyond this average altitude, which varies depending on the weather conditions, the emitted gases can travel great distances and be transformed. This is a covering effect. Near airports, we are in the soup!

Preamble: the aircraft lobby headed by ICAO and IATA works always, and with great success, to minimize local pollution emissions and their impact on the health of populations, as well as greenhouse gas emissions of aircraft and their impact on global warming.


Emissions at low altitude: public health

To understand the issues, the problem can be stated quite simply:


Kerosene is essentially like diesel fuel, so the emissions from airplanes have the same pollutants with the same consequences as diesel fuel, classified by WHO (World Health Organization) as certainly carcinogenic.

The main pollutants are nitrogen oxides, volatile organic compounds (VOC) and fine particulate matter (< PM 2.5).

Aircraft emissions are calculated according to an ICAO international standard. This is a cycle called LTO (Landing & Take Off): landing down from 915m altitude, taxiing to and from terminal and a subsequent takeoff up to 915 m altitude. For each aircraft and engine type the LTO amounts of emissions are calculated for CO2 and nitrogen oxides (NOx) measured as nitrogen dioxide (NO2).

Fine particles and nitrogen oxides are two pollutants having a serious impact on health, in particular the health of the most fragile people. They promulgate not only respiratory and lung disease, including asthma, but also cardiovascular disease. Diesel fuel emissions are considered – as said –  definitely carcinogenic. Finally, remember that the ozone, which also has a bad global warming effect, is the result of a reaction between nitrogen oxides and organics (VOCs for example) triggered by light radiation. Ozone is also itself a greenhouse gas.


Lobby to avoid this kind of topics

After the Volkswagen scandal and more generally the underestimation of emissions from diesel fuel in general, what are the emissions from airplanes for the cycle LTO? A Swiss study to verify the basis of taxation of NOx in a real situation on the airport of Zurich shows that emission calculation is representative. The strategy of the aviation lobby is absolutely to avoid the topic being tackled : a strategy that has been working for many years!

Fine and ultrafine particles: two recent studies show the importance of emissions of ultrafine particles on and around airports. One was in Copenhagen, the other in Los Angeles. They have at least raised concern in the ICAO on the possible consequences for air transport. Aircraft engines emit the most dangerous ultrafine particles (PM 1.0 below). A study published in November 2015 around the airport of Schiphol in Amsterdam confirms this in all respects.

The impact of nitrogen oxides on health is recognized. Until now the air lobby has sought to avoid the subject by issuing false promises. In Europe, Advisory Council for Aeronautics Research in Europe (ACARE) is responsible for making proposals for the future in the context of SESAR, Clean Sky… In 2007, ACARE promised the European political authorities drastic reductions of emissions and noise: by 2020, 50% reduction for noise, 50% reduction on CO2 emissions and 80% discount on nitrogen oxide emissions! This promise has even been included in a law in France (law Grenelle 1), These promises are based upon several research programs concerning both optimization of air traffic and the actual reduction of aircraft emissions for new aircraft. Although it is undeniable that aircraft manufacturers are making progress, they are, unfortunately, insufficient to offset the growth in traffic!


Promises provided some rest…

The outcome of these promises has made for ten years of tranquillity. We can, however, anticipate that in 2018 the air lobby will regretfully explain that the solutions are much more complex, so we must wait (until 2035?).

With the reduction of NOx we are at the centre of the manipulation of the facts. When interviewed, motorist experts confirm that these pollutants resulting from the combustion of kerosene are unfortunately linked to the desire to reduce of consumption related to engines, increase the pressure and the temperature optimization. Research to improve this is not yet given, to this day, convincing results are lacking in terms of efficiency and operational security and the timescales for the aeronautical development are much longer than for cars.

So why announce that a dramatic reduction of the emission of oxides of nitrogen (NOx )?

NOx (mainly NO and NO2) issued by the aircraft at high altitudes, will contribute significantly to global warming through the formation of tropospheric ozone (O3). The lobby continues to deny, but it becomes more and more difficult.

NOx, either directly or transformed into ozone, is a major public health problem, causing pulmonary and cardiovascular diseases. Emergency hospitalisations for asthma in children under 15 years increase by 6% per year around Paris in France!

Analyses around airports show chronic excess regulatory levels of nitrogen oxides!


Address the pollutants

Developed countries have decided to address these pollutants. The technology is operational (SCR, Selective Catalytic Reduction), which transforms the NOx in the presence of a catalyst and an additive ammonia (NH3), nitrogen (80% of the air we breathe) and water vapor. The relevant industries, petrochemicals, energy, cement plants, incinerators, etc. as well as transportation road diesel (since late 2006 in Europe and 2010 in the United States) are being equipped. Diesel cars will come factory equipped with catalytic system by the end of 2016. (Volkswagen, who foresaw a system less expensive and less effective, decided late October to equip all its models with the catalytic system (SCR). NOx emissions have declined by 36% in EU 25 from 1990 to 2007, excluding aviation!

The catalytic system cannot be installed on planes! This means that aviation will move quickly into the spotlights with the charge of damage to the planet and public health. The false promises to reduce NOx emissions by 80% allowed the airline industry to gain a few years of free pollution. Truly a sad result…


Global warming and commercial aviation

One may take an extract from the synthesis of a study of the ICCT, published in 2014, to give the dimension of the problem at the global level. ‘If aviation were a country, it would be ranked 21st in terms of GDP and 7th in terms of CO2 emissions, just behind the Germany and ahead of South Korea’. The growth of air transport is such that experts anticipate that without a major political intervention, there will be a tripling of fuel consumption and therefore emissions by 2050 compared to 2006 worldwide.

Now consider carbon dioxide, CO2! Since 1999, the year of publication of the first report of the IPCC investigator group, specialists in air transport, describing the significant role of air transport in the greenhouse gas emissions, the aviation lobby has kept quiet. Communicating only on CO2 emission (2% worldwide) and thus managing to dismiss all other emissions including NOx, as well as the important role of condensation trails and the resulting cirrus formation. The IPCC  has released a new study in 2009 confirming previous analyses for an overall contribution of aircraft of 4.9% with the share of CO2 alone representing 2% , plus 2.9% for other greenhouse gases and the impact of condensation trails.


Heading for a  catastrophe

These figures take into account only the direct impact direct air transport, calculated on the basis of the global consumption of fuel. However, consider a small simple calculation. If, on average, nations manage to reduce by 50%, for example, global emissions to greenhouse by 2050 excluding aviation sector (basis 2006), air transport would then represent 30% of the total world emissions! Incredible, unimaginable! Where is the mistake?

The aviation lobby, acting at all administrative and political levels in all the major countries of the world with the same ‘story telling’ the same arguments, the same reasoning everywhere and for all the main areas of the economy to the impacts of noise or concerning the role of aviation for greenhouse gas emissions or pollution around airports, has succeeded  in obscuring all the evidence concerning the negative impacts of aviation.

If our politicians do nothing, we are heading for a real catastrophe!





Nitrogen dioxide is an irritant gas that is absorbed by the moist surfaces of the tract respiratory. The toxicity of NO2 comes from its ability to oxidize the constituents of cell membranes. Following a significant exposure to NO2, there is a destruction of a portion of the cells which cover the pulmonary alveoli and are responsible for gas exchange. NO2  reduces the perception of odors, changes in lung function and, in cases of acute, the onset of pulmonary edema. At lower exposure levels, it can contribute to the development of emphysema.


GHG Emissions in Europe.