With the growing proliferation of direct injection, particulate emissions from gasoline engines have become a focus of exhaust emission legislation and research. A key focus is on considering the health effects of particles and their accumulated components, such as polycyclic aromatic hydrocarbons (PAH). In addition to the formation mechanisms and measurement methods, which are based on investigating diesel engine emissions, the morphological and chemical properties are also being examined. The measurement technique and investigation to reduce particulate emissions of diesel engines are advanced. The compliance of these researches to gasoline engines is arguable. Latest gasoline combustion concepts already ensure a very low particulate emission level. Especially fuel design holds a big potential for further improvements. (C) 2015 Elsevier Ltd. All rights reserved.