Public Participation in Decision-Making

The AQD describes the basic principles as to how air quality should be assessed and managed in the Member States. It lists the pollutants for which air quality standards and objectives will be developed and specified in legislation. The pollutants need to be monitored and a breach of the limit values triggers obligations to improve ambient air quality. To this effect, Member States must adopt clean air plans setting out appropriate measures.

The early generation of Air Quality Directives, merged in the AQD, had already established a range of ambient air quality standards which differ in terms of legal consequences and binding nature. The AQD introduced new categories and obligations:

1. New air quality objectives for PM2.5 (fine particles) including the limit value and exposure related objectives.
2. The possibility to discount natural sources of pollution when assessing compliance against limit values.
3. The possibility for time extensions of three years (PM10) or up to five years (NO2, benzene) for complying with limit values.
4. The merging of most of existing legislation into a single directive (except for the Fourth Daughter
   Directive ) with no change to existing air quality objectives

The AQD relies on alert thresholds and limit values. Furthermore, the Member States are obliged, under Article 4 of the AQD to divide the whole of their territory into zones and agglomerations. This repartition has the purpose of organizing the measuring of air pollution according to the contamination of air which exists in each zone or agglomeration.

An alert threshold is a level, beyond which there is a risk to human health from brief exposure for the population as a whole and at which immediate steps are to be taken by the Member State. If the alert thresholds are exceeded, additional obligations are triggered and some immediate steps must be taken (as regards SO2 or NOx) and the Member States shall draw up an action plan in which it indicates the measures which are to be taken in the short term. When certain alert thresholds of air pollution are exceeded, the public shall be informed, so that it can adapt to the increased air pollution. Already when such a risk of exceedance appears is the Member State in question obliged to draw up an action plan in order to reduce the risk or duration of such an exceedance.

The AQD fixed limit values on the concentration of pollutants in the air. These values were binding by January 2010, except for PM2.5 which was binding since 1 January 2015. Beside limit values (protection of human health only), critical levels are set as levels fixed on the basis of scientific knowledge, above which direct adverse effects may occur on some receptors, such as trees, other plants or natural ecosystems but not on humans [Article 2(6)].