Temporal variability of surface ozone at rural locations in Greece

The surface ozone is a pollutant of major concern due to its impact on receptors at currently occurring ambient levels in many regions of the world. The aim of this work is to present the surface ozone's temporal variability patterns over specific rural areas. Hourly ozone concentrations obtained by the rural measuring sites Aliartos (GR01) and Finokalia (GR02) were examined in order to study both the seasonal and the diurnal variation. The analysis showed a strong seasonal variation, with maximum during the warm period of the year and a minimum during the cold period. For the examined periods, a profound ozone-decreasing interannual trend with a decline of ozone levels throughout the examined period at each monitoring site. The diurnal variation at the remote station GR01 is considerably larger than that at the remote station GR02, which is negligible. Nevertheless, the surface's ozone concentration diurnal variation at these measuring sites has a single peak structure. It is remarkable that the surface ozone concentration levels remain lower than the 1-h surface ozone thresholds for human health protection set by the European Union at these rural measuring sites during the examined period. It is remarkable that the annual percentages of the 8-hour mean surface ozone concentrations that are higher than the EC target value (120 mu g m(-3)) can be frequently exceeded during almost all the warm period of the year at these rural measuring sites during the examined periods. Moreover, ozone concentration levels remain lower than the I-hour surface ozone thresholds for human health protection set by the EC at both examined rural measuring sites.