International Civil Aviation and the Local Air Quality

The gasses emitted by aircraft near an airport at altitudes below 3000 feet affect the local air quality. The major pollutants affecting the local air quality are carbon monoxide (CO), particulate material (PM), nitrous oxides (NOx) and volatile hydrocarbons.

The international regulation of aircraft engine emissions is the ICAO Annex 16, Volume II, where the main idea is to reduce emissions at the polluting source. As in the case of noise, ICAO also establishes goals for retiring engines that do not reach the emissions thresholds.

As well as the aircraft manufacturers, engine manufacturers also need to comply with new levels of environmental requirements, investing in research and development to make new propulsion solutions that meet the restriction levels.

The adoption of turbofan engines allowed the aircraft to maintain (or even improve) their performance with reductions in noise, fuel consumption and emission of pollutants. Improvement in combustors led to a reduction of 20% to 40% in NOx emissions. The trend in increasing the engine bypass ratio has been contributing to decreasing the fuel consumption (and emission of pollutants), with higher proportions of engine thrust coming from the flow of the air pushed by the fan.

In fact, the fuel efficiency of aircraft was increased approximately 70%, half of which was due to improvements in engines. Nowadays, approximately 0.5% of all the air passing through the engine is eliminated in the form of pollution.