Directive 96/62/EC laid down the basic principles of a common strategy to be implemented at Community level in the field of ambient air quality assessment and management. Article 4 of that Directive requires the setting of the limit values and alert tresholds for ambient air as regards the atmospheric pollutants referred to in Annex I to the same Directive. The Council has subsequenlty enacted the present Directive for the purposes of: (a) establishing limit values and, as appropriate, alert thr