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Abstract: 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 NO x 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 NO x 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. [Copyright &y& Elsevier]

Abstract: The extent of the exceedance of the EU limit values for nitrogen dioxide (NO2) and particulate matter (PM10) concentrations within the Netherlands is expected to decrease significantly, in the coming years. Whether limit values will actually be exceeded, in the next decade, depends not only on European, national and local policies, but also on the effects of inevitable interannual meteorological fluctuations. An analysis of model calculations and measurements yields variations (1 sigma) in the annual average concentration of about 5% for NO2 and 9% for PM10, due to meteorological fluctuations. These deviations from long-term average concentrations affect assessments of future levels, set against limit values. For instance, an NO2 concentration of 39 μg m−3, estimated for a given year with long-term average meteorology, indicates that it is likely (chance >66%) that the limit value of 40 μg m−3 will not be exceeded in that particular year. At the same time, the estimation also indicates, for example, that this situation is unlikely (change <33%) to continue for three years in a row. However, with an estimated concentration of 38 μg m−3, it is likely that the limit value will not be exceeded for three years in a row. The limit value for the daily average PM10 concentration is equivalent to an annual average of about 32 μg m−3. This threshold is unlikely to be exceeded for three years in a row, when an annual average concentration of 29 μg m−3 is estimated. Interannual variations in concentrations of NO2 and PM10 are linked to large-scale meteorological fluctuations. Therefore, similar results can be expected for other European countries. [Copyright &y& Elsevier]