By means of an amendment of the 22nd ordinance on the implementation of the Federal Immission Control Act (22. Verordnung zur Durchführung des Bundes-Immissionsschutzgesetzes (22nd BImSchV)) the requirements of the EU directive 1996/62/EC on ambient air quality assessment and management and the related directive 1999/30/EC on critical values for the ground level conentrations (GLC) of various air pollutants. were converted into national law. If the limit values are exceeded, the appropriate authority has to elaborate air pollution control plans, and if there is a danger that the limit values are exceeded, action plans must be established by local authorities, if critical values loom to be exceeded.. The plans may include extensive measures to the point of restrictions for motor traffic. Within the scope of the air pollution control planning, appropriatemeasures to lower the pollution level must be pointed out and taken in case that the limit values are exceeded.

Müller-BBM, leading engineering company in acoustics and air monitoring, situated in Munich, has started a two-year research project on means of reduction of airborne particulates caused by road traffic. The scope of the project is to study the ability of porous asphalts (PA) to lower particulate matter (PM) emissions of the vehicles. PA have already proven as excellent materials for the construction of low-noise motorways, The idea is, that particles are transported into the pores of the PA due to sedimentation, absorbed therein, and thus kept from resuspension into the atmosphere.

If PA turns out to have a positive effect on PM-GLCs, road construction work cannot only contribute to noise reduction, but also help to improve air quality. By means of PM emission reduction, restrictive measures as traffic bans can be avoided.