Before implementing the third European directive, the member states of the European Union should assess the air quality for ozone in their countries. Measerements and modelling results indicate that the target value for the protection of human health and vegetation in 2010 will not be exceeded. The ozone concentrations measured at each sampling point during the years 1997-2001 show that the long-term objectives for the protection of human health and vegetation were exceeded in all zones and agglomerations. As a consequence, all zones and agglomerations have been included in the strictest monitoring regime. Where measurements are the sole source of information used to assess ambient air quality for ozone, the third daughter directive requires that under regime 1, data is to be obtained from 31 sampling points, divided between sites in urban areas (3), suburban areas (12) and rural (regional) areas (16). A comparison of current numbers and locations of ozone sampling points showed a need for additional points for monitoring ozone and nitrogen dioxide particularly in suburban areas of zones and agglomerations.