Air quality did improve significantly over the past years as shown by available trends and the assessments performed under the Convention on Long Range Transboundary air pollution (CLRTAP) and the EU Thematic Strategy on Air Pollution (TSAP). As a consequence, transboundary transport gains increasing importance which can clearly be seen e.g. in low emission zones like Leipzig. However, particulate mass is still a health issue: concentrations decrease slowly, and further exceedances of limit values can be expected especially for urban areas. Particles filters are considered a substantial success with significant positive health effects especially in abatement of Diesel engine emissions. Modern gasoline engines now emit more particles compared to Diesel engines with filters. Particle number limits are now required as metric to reach next levels in air pollution reduction e.g. to define meaningful values for low emission zones. Jet turbines emit UFP less agglomerated, more compact, and smaller than e.g. Diesel soot; with increasing thrust primary particle size grows and internal particle structure changes from amorphous to semi-crystalline. Regulatory developments for future non-volatile particle mass and number emissions regulation are ongoing as well as airport initiatives for scientifically robust and improved UFP monitoring and health studies focusing on aircraft gas turbine emissions. While primary sources of UFP are rather well known and mitigation options are available this is much less well known for secondary sources. An abatement strategy for traffic could be dedicated mobility concepts and e-mobility. New standards for air traffic are on the way, however, air traffic is increasing strongly and thus requires accelerated research for the effects of UFP related with jet engines. The final discussion about emissions and abatement strategies led to the conclusions that it is the responsibility of policy to set emission limits especially for pollutants which are linked like NOx and UFP. A limit value for NO2 was adopted in 1999, came into force in 2010, and is still not complied to everywhere. Public awareness is needed and an initiative for UFP limits as well. Aircraft engine emissions are a special case since they are regulated by global standards. Better air quality standards related to health effects are needed suitable not only for toxicology but also for epidemiology. Abatement measures for UFP should take into account their health costs and the importance of long range transport.

The 6th Symposium

Increasing applications of man-made nanomaterials add to the problem, e.g. after incineration at the end of their lifetime. A further interest in UFP’s results from their specific role in atmospheric processes such as cloud formation and precipitation and, in fact, in climate.
The relation between UFP and human health and that of UFP and climate are both areas of active research and cross-links between these fields are found nowadays.
The subtitle of the conference series: “air quality and climate” reflects this development.


Particulate matter metrics

Present policies to decrease exposure to particulate mat- ter make use of the mass-based metrics PM10/PM2.5, which do not properly represent all risks for human health. EFCA is, therefore, in favour of the development of a fraction-by-fraction approach on particulate matter, both with respect to size and chemical composition. It already recommended European policymakers the int- roduction of Black Carbon Particles as additional metric in the Air Quality Directive. The organizers trust that EFCA’s 6th Ultrafine Particles Symposium 2017 will again feature the most recent scientific progress in the field and so contribute to policy-relevant developments which improve the dialogue with policymakers in Europe. 


 The Symposium has gained visibility by permanently moving to Brussels and attracts an effective mix of EU represen- tatives and scientists. EFCA and KIT, together with GUS and CEEES are pleased to organize this event again. We cordially invite all experts to contribute actively and hope to see you again at the State representation of Baden- Württemberg in Brussels in May 2017.