Letter: A
Abrasion The cause of tyre tread (see entry) wear. Determined by the phenomena of friction between the tread itself and the ground. Heavily influenced by temperature and abnormal tyre inflation pressures.
Aromatic hydrocarbons (CO2) Organic compounds whose structures are characterized by the presence of at least benzene ring.
Atmospheric emission Any solid, liquid or gaseous substance introduced to the atmosphere from an industrial plant or any other source that may produce atmospheric pollution.