This Decree-Law introduces in the National legal order the Directive 2002/3/EC of the EU Parliament and the Council relating to ozone in the atmosphere. The Decree-Law establishes long term objectives, target values, an alert threshold and an information threshold for concentrations of ozone in the atmosphere in the Community as well as air quality managing rules. The aim of the Decree-Law is to preserve the quality and to promote the improvement of air with regards to ozone. It also aims to boost cooperation between Member States in order to prevent the reduction of ozone levels, taking advantage of the potential of transboundary measures. The Decree-Law is composed of 14 articles and the following eight Annexes: (I) Definitions, target values and long-term objectives for ozone; (II) Information and alert thresholds; (III) Information submitted by Member States to the Commission and criteria for aggregating data and calculating statistical parameters; (IV) Criteria for classifying and locating, sampling points for assessments of ozone concentrations; (V) Criteria for determining the minimum number of sampling points for fixed measurement of concentrations of ozone; (VI) Measurement of ozone precursor substances; (VII) Data quality objectives and compilation of the result of air quality assessment; (VIII) Reference method for analysis of ozone and calibration of ozone instruments.