apron means a defined area intended to accommodate aircraft for purposes of loading or unloading passengers, mail or cargo, fuelling, parking or maintenance;
aeroplane means a power-driven heavier-than-air aircraft, deriving its lift in flight chiefly from aerodynamic reactions on surfaces which remain fixed under given conditions of flight;
Semitrailer means every vehicle of the trailer type so designed and used in conjunction with a
Seaplane means a fixed wing aircraft which is designed for taking off and landing on water and includes amphibians operated as seaplanes;
Oxides of nitrogen means the sum of the volume mixing ratio (ppbv) of nitrogen monoxide (nitric oxide) and nitrogen dioxide expressed in units of mass concentration of nitrogen dioxide (μg/m3);