A study, conducted by the German TUEV Nord in November 2013 and published by the Brussels-based environmental lobby group Transport & Environment, says that new direct-injection gasoline (GDI) engines emit 1,000 times more particles than their predecessors and 10 times more than modern diesel engines.
Air pollution in Europe is estimated to contribute to over 400,000 deaths and cause €330 to €940 billion in damage to the economy annually. In fact, 90% of the population is exposed to levels of particulate pollution that represent a health risk and one third lives in areas above permitted limits. According to the study, new GDI-powered vehicles could take over the lead in particulate pollution among combustion engine-powered vehicles while modern diesels have become more environmentally sustainable.
http://www.achatespower.com/diesel-engine-blog/2014/01/07/are-diesels-cleaner-than-gasoline-engines/