Berlin Air: Cleanest in EuropeThe main reason for Berlin’s dramatic reduction of soot was the introduction of a low-emission zone (LEZ) of 34 square miles in 2008. SavePrintChristian Watjen9/8/2011|Updated: 10/1/2015We had a problem loading this article. Please enable javascript or use a different browser. If the issue persists, please visit our help center.