In its opinion of 18 December 1991 on the Commission's proposal for a Council Directive on ozone (COM(91) 220 of 24.6.1991) the Economic and Social Committee notes that air pollution by photochemical oxidants is one of the major environmental threats to mankind, and has damaging effects on human health, flora and fauna and materials. However, ozone concentration measurement in the Member States is neither comparable nor standardized, and does not allow an overall assessment of the problem. While the aim of the proposed Directive is to harmonize and coordinate the collection of data, the Committee feels that the information currently available could justify accelerated action, starting by identifying measures to curb pollution at source. Research into potential measures to limit photochemical precursors should be stepped up. The Committee also urges the Commission to undertake research projects focusing on the systematic study of ozone patterns and movements in the air in conjunction with centres recording atmospheric data. The European Environment Agency, once established, is the appropriate body for collecting and harmonizing data and subsequently defining the required measures, and the Committee therefore calls on the Council to determine the Agency's seat and responsibilities, to ensure that present and future Directives have the benefit of vital technical and planning backup.