A SUMMER AIR-POLLUTION STUDY IN ATHENS, GREECE

During a photochemical episode in Sep:ember 1994, we studied transport and distribution of primary and secondary air pollutants in Athens, G reece, using a research aircraft instrumented for meteorological and a ir chemistry measurements, ard ground-based air-pollution-monitoring s tations. We performed a total of 9 flights on 7 days under various met eorological conditions and pollution levels. We report typical polluta nt mixing ratios for the background boundary layer. Sea breezes of var ious intensities were observed during all our noon flights. The set br eezes carried air pollution of apparently different origin and photoch emical age, as indicated by the O-3/NOy ratios. The pollution levels w ithin the sea breezes were, however, low compared to those in the city of Athens. Under favorable meteorological conditions, the sea breeze could penetrate the entire Athens basin, resulting in an upward flow a t the foothills of Parnitha and Pendeli Mts., and filling the lower tr oposphere with high levels of air pollution at altitudes of up to 2000 m and more. From these layers of high photochemical activity (O-3 lev els up to 200 ppb), air pollution may have been incorporated into long -range transport. (C) 1998 Elsevier Science Ltd. All rights reserved.