To reduce the emissions from traffic is urgent. In order to create action plans against air pollutions a number of facts and circumstances must be faced. These circumstances do complicate the search for an optimal action plan. The circumstances are for example: (1) the changing nature of the problem: from being a problem of lead and carbon monoxide, the focus has more and more become emissions of nitrogen oxides and carbon dioxide. What will be the next development ? Extended and deepened knowledge often leads to a revised approach to problems, threat scenarios and conceivable action programmes; (2) many dimensions and cross-connections between targets, resources and interested parties: there is a risk parties: there is a risk that the environmental aspect, which is important, becomes too dominant and obscures the view of the whole. Traffic and the environment is a problem and subject area with many dimensions. In general, there are no simple, straightforward and uncontroversial answers or solutions when it comes to choosing countermeasures or action progammes against air pollution. Several explanatory circumstances may be pointed out in this context, one of the main ones being that most - if not all - countermeasures and actions aimed at reducing the effects of emission/imissions often have consequences apart from those which are primarily intended; and (3) the estimated values for future emissions are very uncertain: there is always a risk of underestimating or overestimating the problem of emissions, with the accompanying risk of incorrect use of resources against emissions. (A)
Abstract