Higher than expected NOx emission from trucks may affect attainability of NO2 limit values in the Netherlands

In past years, the European limit value for average annual NO2 concentration has been exceeded in city streets and along motorways in the Netherlands. By 2015 the limit value must be adhered to in the Netherlands. Although the total road length for which exceedance is likely is expected to decrease over the coming years, exceedances may still occur by 2015. Future NO2 concentrations not only depend on economic growth, current and proposed policies, and on inevitable meteorological fluctuations, they also depend on the effectiveness of technical measures to reduce emissions. New emission measurements for heavy-duty vehicles in the Euro-V (and Euro-III) emission standard categories, carried out under typical Dutch driving conditions, have revealed that real-world NOx emissions from these trucks are significantly higher than was previously estimated based on the reduction steps in the Euro emission standards. Emission levels were higher, by about a factor of three, along city streets, and 10 to 40% higher along motorways. These higher emission levels resulted in higher estimated national NOx emissions, increasing from 250kt to 264kt, compared with the national emission ceiling of 260kt, to be adhered to by 2010. The higher emissions more than double the total road length with possible exceedance (chance >33%) of the NO2 limit value; from about 100km to about 250km along cities streets and motorways, by 2015. These higher emissions from trucks, therefore, affect the chances of the limit values being adhered to, in time, everywhere in the Netherlands. © 2011 Elsevier Ltd.