Identification of the Influence of African Dust on PM10 Concentrations at the Athens Air Quality Monitoring Network during the Period 2001-2010

The objective of this work was to identify Sahara dust intrusions and quantify their contribution to annual and daily PM10 concentrations over the Athens Metropolitan Area (AMA) during the period 2001-2010. Additionally, extreme PM10 values attributed to large forest fires and volcanic emissions or the synergy of the above with African dust intrusions have been identified. It was found that the concentrations of PM10 during the period studied exceeded the European Union's Air Quality Standard (EU AQS) value at most of the traffic urban (TU) stations. Most of the extreme values were attributed to dust events or large forest fires. The contribution from African dust to PM10 concentrations on days with events and exceedances of the EU AQS was approximately 50% at TU stations and 72% at the background suburban stations (BS). Most of the African dust events contributed about 5 mu g/m(3) to 34 mu g/m(3) to the daily PM10 concentrations, whereas the average contribution to annual PM10 concentrations was approximately 8.6 +/- 1.8 mu g/m(3) i.e., 22.2 +/- 7.5%. During the decade, no clear interannual relationship was observed between the African dust contribution and the frequency and intensity of events. The more frequent and severe episodes occurred during spring, while less frequent and less severe episodes occurred during summer. After the extraction of the African dust load the annual and daily AQS was exceeded in 2010 at only one TU station. The average annual contribution of African dust to the exceedances was approximately 36% at TU stations and 58% at BS stations.