With a view to improving air quality and meeting air limit values quickly, and at the same time allowing for new spatial development projects, the Dutch Cabinet has issued in November 2006 a new law on air quality. A key element of this law is the National Air Quality Co-operation Plan. The principal aim of the National Plan is to set up a co-operation programme between central government and the provincial and municipal authorities. To support the process of identifying areas where air quality problems remain unabated and identifying the policy actions to be taken by the various authorities, a software application called the Clean Air Policy Tool (CAPT-NL)was developed. The Clean Air Policy Tool maps the air quality along the entire Dutch road network. The software tool assists users in resolving NO2and PM10 exceedances along roads by implementing generic regional and location-specific policy measures. A distinction is made between the main road network and secondary road network. Air quality calculations for the main road network use the VLW model. Those for the secondary road network arebased on the CAR II method. The Clean Air Policy Tool enables users to analyse the air quality situation at different levels of scale, and evaluatethe effectiveness of two types of action. The first are generic regional policy measures, which cover a larger area. The aim of this type of measure is to reduce the volume of car traffic and goods vehicle traffic, and tomake public transport buses cleaner. Then there are location-specific measures, which are specifically aimed at resolving individual hot spots. They include measures to influence the flow of traffic in specific places, encourage the use of vehicles with environmentally-friendly technology, and dispersion measures that have a direct impact on concentration levels. Ultimately, the Clean Air Policy Tool provides a forecast for the year in which all exceedances of objectives are expected to be resolved. The first calculations done with the Clean Air Policy Tool reveal the following: Over the next few years, national and international at-source policy actions are likely to lead to a substantial reduction in the number of emission exceedances; PM10 emission exceedances, in particular, are expected largely todisappear as a result of national and international at-source policies. NO2 emission exceedances, however, will prove a persistent problem. Under the best-case scenario (full-policy scenario), NO2 emission exceedances arelikely to continue to exist along more than 70 kilometres of secondary roads in 2015. Measured in kilometers the number of exceedances on the urbannetwork and along the motorway network are more or less the same (both about 800 km for NO2). But the expected decrease along the urban network is much larger than along the motorway network. More effort will be needed tosolve the remaining exceedances along the motorway network. What remains of NO2 emission exceedances are likely to be found in the four major conurbations. In fact, in 2015, 85% of remaining exceedances are expected to befound in the four conurbations. As for the PM10 emission exceedances remaining on the secondary road network, they are likely to be almost entirelylimited to the four major cities. Accordingly, policy efforts will more than proportionally have to be directed at the four major cities. Local authorities are unlikely to be able to resolve all remaining hot spots on their own. There are, however, possibilities for local authorities to reduce the number of emission exceedances through local policy measures. With a relatively minor effort, they could reduce the number of NO2 hot spots by approximately 20% and the number of PM10 hot spots by approximately 10%. For the covering abstract see ITRD E137145.
Abstract