Pollution from aircraft

Pollution from aircraft emissions has been a cause for concern since jet aircraft first took to the skies in the 1950s. At that time it was the highly visible plumes of exhaust gases and their effect on local air quality which attracted the attention of regulators and the scientific community. In recent years the debate has shifted to questioning the effect of aircraft emissions on the upper atmosphere and how the aviation community should respond. Awareness has been heightened by the forecast rate of growth of air transport, perhaps a tripling in the number of passenger kilometres by 2015. Aircraft emit a number of different pollutants. Some, such as CO₂, H₂O and SO₂ are direct products of burning carbon fuel, and are emitted in a constant ratio to fuel use. Others, such as CO, hydrocarbons (HC) and oxides of nitrogen (NO_x), are affected by combustion conditions