As I have been permanently about the air-pollution in Athens, I should be fair and post about the new measures to be applied as of September 1 st 2012 and allowing only low-emissions car to drive through the centre of the Greek capital.
Below the new measure as posted by daily Kathimerini:
The restrictions preventing some cars from entering the center of Athens have been lifted for the summer, marking the end of the so-called “ring” based on license plate numbers, which began in 1982 to combat pollution and congestion.
From September 1, only low-emission cars will only be allowed to enter central Athens during peak hours.
Under the new scheme, only cars which comply with the Euro 5 emissions standard introduced in September 2009 will be allowed to drive into or through the center.
Vehicles that meet the Euro 4 standard but emit less than 140 g/km of carbon and hybrid cars will also be allowed access at all times.
Hopefully before September we will know what cars will be allowed to drive through and at which hours.