1. Introduction

This report deals with the status of pollution caused by tropospheric ozone in the European Union in 1994, '95 and '96, as it was announced under Article 8 of the current Council Directive on Air Pollution by Ozone (92/72/EEC; EC, 1992a), This article states that "as soon as possible, and not later than at the end of a four year period following the implementation of this Directive, the Commission shall submit to the Council a report on the information collected and on the evaluation of photochemical pollution in the Community". This report is intended to be complementary to the report on an abatement strategy for ozone, which also falls under Article 8 and is to be drafted by the so-called Ad-hoc Working Group on the Ozone Directive and Reduction Strategy Development, supported by IIASA as a consultant. Furthermore, the present report on the status of pollution by tropospheric ozone is to serve as a companion to a position paper which shall lead to a proposal for a Daughter Directive for ozone to be developed under the Council Directive on Ambient Air Quality Assessment and Management (96/62/EC).

Pollution from photo-oxidants that has been damaging the health of the European population and vitality of ecosystems for several decades is a major, complex problem. Anthropogenic emissions of oxides of nitrogen and hydrocarbons, mainly released from transport activities and solvent usage, are the dominant cause of many aspects of the photochemical pollution problem. Biogenic sources of hydrocarbons are also of importance. The Commission has put many efforts into combating ozone during the past decade. The fourth Community Action Programme on the Environment put forward the possibility of action on ozone with view to its harmful effects. The fifth Environment Action Programme (5EAP), issued in 1992, set emission reduction targets for the ozone precursors and aimed at zero exceedances of the levels defined by the WHO guidelines (EC, 1992b), which were introduced in terms of thresholds in the current Council Directive on Air Pollution by Ozone. In addition to establishing the concentration thresholds, this Directive laid down a harmonised procedure for monitoring ozone and precursors and exchanging data. It also provided for arrangements to inform and warn the population if necessary. The present report assesses the information collected between 1994 and 1996 in the framework of the Directive and by doing so assesses the status of photochemical pollution in the European Union.

The data reported to the Commission in the framework of the Directive, in particular for 1995, was the leading source of information in the current work. However, in many cases information from the UN-ECE, EUROTRAC and DGXII programmes was of vital importance to complete the assessment. In subsequent sections we will discuss the background to the occurrence of tropospheric ozone, the EU-wide ozone monitoring network, trends in ozone precursor emissions, exceedances of current thresholds and assessments of numbers of individuals and ecosystems exposed to these exceedances.

This report has been drafted by the European Topic Centre on Air Quality (ETC-AQ), supported by WHO and Joint Research Centre - European Reference Laboratory for Air Pollution (JRC-ERLAP).

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