Analysis of the 11-year Record (1987-1997) of Air Pollution measurements in Athens, Greece. Part II: Photochemical air pollutants

This paper deals with the analysis of atmospheric concentrations of secondary photochemical air pollutants in Athens for the 11-year period 1987-1997. Photochemical pollution, which seems to be the most serious air pollution problem in Athens, is originating mainly from the transformation of car emissions, and its control is a quite complicated task since various non-linear phenomena are implicated. The main subject of this work is to examine whether the substantial decrease observed in the concentrations of the primary air pollutants, especially for CO, in Athens in recent years is followed by a corresponding decrease in the photochemical air pollutant levels in the Athens basin, while the characteristics of the seasonal and diurnal profiles of photochemical pollution are investigated. In this context, the interannual variability of O3 and OX (O3 + NO2) is examined for the peripheral stations of Liossia (10 km northwest from city center) and Smyrni (5 km southeast), which have continuous records of O3 and NO2 data since 1987. In general, the concentrations of the photochemical pollutants (especially OX) in both examined stations are comparable, while they seem to have remained essentially at the same levels since 1990. Further pollution abatement measures should be taken in order to comply with the EU ozone air pollution standards in the Athens basin.