Although the chemical smog that smothered much of Athens during the 1980s is now much diminished, Greece still tops the European league in forms of air pollution that nobody paid much attention to 20 years ago. Two new studies made public yesterday show that Greek cities have the highest levels of airborne particles, or aerosols, in Europe, while Greece has the worst showing for ozone, the main component of summer smog. In both cases, pollution was worst in the summer – when Athens is to host the 2004 Olympic Games. A survey of 19 European cities carried out by the Earlinet network on behalf of the European Union found the highest concentrations of aerosols in the air of Athens and Thessaloniki. Other cities monitored were Paris, Hamburg, Munich, Rome, Barcelona and Minsk. «The main source of airborne particles in Athens and Thessaloniki is, of course, car traffic,» National Technical University of Athens (NTUA) Assistant Professor A. Papayiannis told Kathimerini. The NTUA is handling the Athens branch of the survey, which started in 2000. Papayiannis said both cities also suffer from «imported pollution» – blown over from Turkey, the Black Sea, Central Europe and the Sahara. In the last case, the problem is created by desert sand which contains toxic substances and bacteria. Over the past 2.5 years, NTUA scientists noted 37 instances of Saharan sand being carried to Athens, and 16 to Thessaloniki. In both cases, pollution was worst in the summer. Meanwhile, the European Environment Agency (EAA) said yesterday that Greece had the highest number of days (68) this summer when ozone pollution was above the EU threshold – 180 micrograms per cubic meter of air, averaged over one hour – followed by France (56), Italy and Spain.