The impacts of anthropogenic emissions from the maritime transport and from the countries neighboring Greece on the maximum ground-level ozone concentrations over Greece were studied. Ozone concentrations were simulated across a part of the Eastern Mediterranean during a summer period using a modeling system that consisted of the photochemical Urban Airshed Model known as UAM-V coupled with the meteorological mesoscale model known as MM5. Simulated, maximum hourly ozone concentrations were higher over continental and maritime areas of Greece influenced by the emissions of the large urban agglomerations. When air quality simulations were performed assuming zero maritime transport emissions, the greater part of Greece experienced reductions in maximum ozone levels. Over the continental part of the country, the largest ozone reductions occurred along the coastline of southern and western Greece and were approximately 20 ppb. Over maritime areas, the decreases in maximum ozone concentrations were more pronounced. However, in the regions influenced by high amounts of nitrogen oxides emitted from the sea transport activities, the 03 concentrations were increased. The impact of anthropogenic emissions from all continental areas within the modeling domain, other than Greece, on the maximum ozone concentrations over Greece was small. Considering that the emission inventory for Greece was more detailed, while the official emission data for some of the countries in the modeling domain were generally poor, the assessed impact might have been underestimated. (C) 2008 Elsevier B.V. All rights reserved.