"Commercial air travel is expected to double in the next 20 years, which will in turn increase the amount of contaminants emitted to the atmosphere. The following contaminants are emitted during the different phases of operation:


NITROGEN OXIDES (NOx) – which includes nitrogen oxide (NO) and nitrogen dioxide (NO2)

CARBON MONOXIDE (CO)

UNBURNED HYDROCARBONS – which have almost been completed eliminated from the exhaust stream due to newer engine technologies

SULPHUR OXIDES

PARTICULATE MATTER (PM) – which leaves the exhaust as carbon black soot

VOLATILE ORGANIC COMPOUNDS (VOCS) – such as benzene and acrolein

OZONE (O3)– which is formed from the nitrogen oxides and volatile organic compounds emitted

SEMI-VOLATILE ORGANIC COMPOUNDS (SVOCS)

METALS

NOISE – this contaminant is discussed in the Aircraft Noise section of the ICAO site

ODOUR"
http://www.icao.int/environmental-protection/Pages/Contaminants.aspx

"Health Effects


Exposure to the contaminants listed above can result in serious health effects. The table presented below lists some of these effects. Local and regional air quality officials are responsible for creating standards to protect human health from the adverse effects of these contaminants."
http://www.icao.int/environmental-protection/Pages/Contaminants.aspx