pdf
235 KByte
 

High NO2 levels: Ongoing Need for Action on Diesel Emissions

Speech of Dr. habil. Uwe Lahl, VDA Technical Congress, 2.-3. April 2008 in Ludwigsburg

As from January 1st, 2010, two ambient air quality limit values for nitrogen dioxide (NO2), which have been adopted in 1999, have to be met in the EU. These two limit values are a one hour average concentration of 200 µg/m³ and an annual average concentration of 40 µg/m³. Whereas the one hour value is complied with nearly everywhere today, the annual average concentration is exceeded today at many monitoring stations, particularly at roadside stations. Further reductions of NO2 concentrations are thus essential to comply with the annual limit value by 2010.

The main cause of the high NO2 levels is motor vehicle exhaust emissions of NOx produced during the combustion of motor fuel. Vehicles largely emit nitrogen monoxide (NO), which is converted into NO2 in the course of chemical reactions in the air. Moreover, the contribution of directly emitted nitrogen dioxide (NO2) to emission levels is greater than previously assumed. These direct NO2 emissions have increased in recent years as a result of modern exhaust gas treatment technologies, particularly in modern diesel engines.

This development means that despite the continuing decrease in NOx emissions by motor traffic, timely compliance with the annual limit value for NO2 will not be possible without great efforts and measures at all levels. The focus of these efforts will be on the traffic sector. The Ministry has therefore reached agreement with the VDA (German Association of the Automotive Industry) on the preparation of an “Action Plan NO2” containing measures and an assessment of the impacts of these measures. In this paper a first overview is given about different possibilities to reduce NO2 levels. The VDA has also promised to submit proposals to the Ministry.