Road traffic emissions impact on air quality of the Greater Athens Area based on a 20 year emissions inventory.

During the last decades, the Greater Athens Area (GAA), among many other urban agglomerations, faces atmospheric pollution problems mainly associated with high levels of particulates, nitrogen dioxide and ozone. The major pollution source for the GAA is road transportation. In this sense, the aim of this work was to investigate the existence of a direct relationship linking air pollutant concentration levels and road traffic emissions. To this aim, air pollutant emissions from road traffic were calculated for the period 1990-2009 and then the relationship with the corresponding air pollutant concentrations was investigated. The calculated results have revealed that all pollutants examined show a strong decreasing trend whereas the age of the vehicles and the corresponding engine technology determine the amount of the pollutants emitted. In addition, the NO(2)/NO(x) emission ratio presents a constant increase in the course of the years, according to the respective NO(2)/NO(x) concentration ratio. Furthermore, the comparison between emission calculations and the corresponding measured concentrations shows a highly significant correlation providing therefore evidence to policy makers that all pollution abatement measures can be defined and assessed with regard to their anticipated effect on air pollutant emissions. Detailed analysis of the 2009 emissions shows that, in general, passenger cars are the major polluters for CO, NMVOCs and CH(4), whereas PM(10) and NO(x) are mostly associated with heavy duty vehicles (HDVs). Finally, it appears that vehicles aged more than 15 years are responsible for the major part of the air pollutants emitted.