The discussion about the urban air pollution control strongly emphasised the particulate matters during the last years. In order to reduce the PM-concentration, comprehensive measures were implemented for the reduction. Thereby the EU-air threshold for nitrogen oxide that will be binding from 2010 was less considered by the public.
At many highly frequented roads these limit values are often exceeded. The main reason for this can be found in the direct NO₂-emissions of road-vehicles. With the implementation of exhaust aftertreatment technologies the NO₂-percentage of NO_x caused by diesel engines partly increased.

Therefore the FAD raised the question if a simultaneous PM- and NO₂-reduction will be possible. In order to find an answer, the workshop


was organized in cooperation with the Umweltbundesamt (German Federal Environmental Agency) on 24 and 25 March 2010 in Dresden.

101 representatives of the industry, research institutes and public authorities from four countries attended the workshop.

The first day focused the measurement technology and measurement methods for NO₂ in the exhaust of diesel engines.

In an overview lecture Kurt Engeljehringer (AVL List GmbH) showed the chances and limits of the measurement technology. Daniel Scheder (Horiba Europe GmbH) spoke about new laser based methods for the determination of NO₂ and other nitrogen oxide compounds. In a very practically oriented presentation Wolfgang Kolberg (Saxon Junkalor GmbH) explained the exhaust emission test from the perspective of a measurement devices manufacturer. Subsequently Berthold Arlitt (AVL Emission test Systems) spoke about the possibilities of the FTIR measurement technology for the determination of nitrogen oxide and other components. Moreover, Oliver Franken (Sensors Europe GmbH) introduced with his contribution the simultaneous measurement of NO and NO₂ with the help of NDUV measurement technology.

Besides measurement devices manufacturers also research institutes and measurement device applicants gave their presentation. Dr. Raimund Brunner (Fraunhofer IPM) introduced quick laser-based exhaust measurement technology for the unaltered measurement of NO_x”. Beate Heller (Volkswagen AG) reported about experiences with the measurement of NO and NO₂ at the roller dynamometer test bench.

At the end of the first workshop day the participants met in the restaurant PulverTurm in the city center of Dresden in order to continue the exchange of experiences and discussions in a relaxed atmosphere.

The second day focused the development of the emission legislation in respect to NO₂, the occupational health and safety aspect of nitrogen oxides as well as the NO₂-reduction possibilities of the industry.

Prof. Dr.-Ing. G. Zikoridse (FAD e.V./HTW Dresden) opened the second day with a short introduction into the topic. His speech was followed by the greeting of Marion Wichmann-Fiebig (Umweltbundesamt) who in her greeting pointed out the position of the Umweltbundesamt (German Federal Environmental Agency) in regard to traffic-caused NO₂.

Richard Dorenkamp (Volkswagen AG) spoke about “The challenge to reduce NO₂-emissions – Volkswagen answers”. About the “NO₂-Emission-Measurement of commercial vehicles retrofitet with particle reduction systems” Dr. Susanne Witt (Umweltbundesamt) reported. Subsequently Dr. Jörg Spengler, INTERKAT GmbH, introduced the catalytic coating for NO₂-optimised particle filter systems. The next contribution was held by Frank Dünnebeil (ifeu) who explained the results of the latest analyses of his institute regarding the causes and the future development of NO₂. An overview over the diesel soot, NO and NO₂ limit values and the exposure situation at work places was given by Dr. Dirk Dahmann (BG RCI, Institut für Gefahrstoffforschung). The next presentation was held by Laurent Rocher (Rhodia Operations). He referred to the additive supported filter regeneration and its NO₂-reduction potential. Finally Klaus Schrewe (HJS Fahrzeugtechnik GmbH & Co. KG) spoke about experiences of his company regarding NO₂-selectivity of full and bypassfilter for the retrofit application.

Finally all speakers discussed with the participants the topic in the panel discussion that was lead by Professor Zikoridse. At the end Professor Zikoridse summarized the workshop as follows:

The European legislation on air quality to protect human health does not limit the total of nitrogen oxide (NO_x) but nitrogen dioxide (NO₂) only. According to EU-directive 1999/30/EC, an annual mean NO₂-concentration of 40 µg/m³ has to be met as from 2010. This annual mean nitrogen dioxide concentration is exceeded at many highly frequented streets today. The main reason can be found in the direct NO₂-emissions from on-road vehicles. Inspite of the reduced nitrogen oxide emissions the limit value for nitrogen dioxide is still exceeded.

As result of the implementation of exhaust aftertreatment technologies, especially particulate filter systems for the reduction of PM-emissions, the NO₂-share of NO_x from diesel engines increased.

The reason can be found in the increasing primary NO2-emissions of modern diesel passenger cars and in the rising kilometrage of diesel passenger cars. Besides this the NO₂-share formed by emitted NO by an atmospheric chemical reaction, primarily with ozone cannot be neglected.

The future NO₂-limit value can only be kept, if a significant reduction of primary NO₂ and NO₂ formed by atmospheric chemical reactions will be reached. The significant reduction of the traffic caused nitrogen oxide emissions is not displayed in the current nitrogen dioxide exposure.

Due to the introduction of the new European limit value Euro 5 and Euro 6 for passenger cars not only a further minimization of the NO_x-emissions can be expected but also a significant reduction of the NO₂-emissions. But it requires that the exhaust aftertreatment technology in new passenger cars reduces NO_x-emissions as well as NO₂-emissions in the urban traffic. Moreover the implementation of the Euro VI limit value for trucks will reduce NO_x-emissions of the traffic and by this also NO₂.

Conclusion:

Despite of the technical challenge to sustainably reach the tight emission and imission limit values a simultaneous reduction of PM and NO₂-emissions will be possible.

We thank all speakers and exhibitors for their effort that allowed the workshop to become a success. Furthermore we thank the participants for coming and discussing with us.

All presentations are summarized on a CD an can be ordered in the FAD-office.