The 1996 EC Directive on IPPC, which takes effect next October, obliges the European Commission to publish an inventory of the "principal emissions and sources responsible" every three years, based on data supplied by Member States. Details were left to be thrashed out by a technical committee of national officials chaired by the Commission. The committee's first meeting was in November 1997, but much work remains to be done.
Some building-blocks for a European PER already exist in the form of national or regional PERs. But these vary widely in coverage and other key features which will require a measure of harmonisation before an EC inventory can be built up.
For instance, apart from the UK - whose Chemical Release Inventory has not been updated since 1994 - the Netherlands and Ireland, the existing PERs cover single environmental media rather than releases to air, water and land.
Similarly, Member States use different thresholds to trigger reporting of emissions to their PERs by industry, as well as different criteria to determine which substances and wastes have to be reported.
The Swedish EPA's study, which was part-funded by the Commission, surveyed the existing PER systems to provide a basis for developing a European inventory. The report will be debated by the technical committee at its next meeting in December.
Because of the wide range of experience with PERs among Member States, the report advocates a step-by-step approach towards a European inventory.
For example, reporting of substances to the PER should be developed in three stages, the study recommends. Substances to be reported in the first two stages are proposed. They were selected on the grounds that they are released in large quantities and already have to be reported to existing national inventories or under international agreements, or because they are released in relatively large quantities from a variety of sectors subject to the IPPC Directive.
Eight substances would be reportable in the first stage. They are all air pollutants implicated in global warming, acidification or ozone pollution (see below).
Eighteen substances or groups of substances would be reportable in the second stage. Almost half are mainly air pollutants, but the list also includes metals released in significant quantities to water and as wastes (see below).
Mercury & compoundsZ
inc & compounds
Copper & compounds
Lead & compounds
Chromium & compounds
Cadmium & compounds
Arsenic & compounds
Nickel & compounds
A list of reportable substances for the third phase has not been proposed at this stage. Instead, the report suggests that it should include metals and organohalogens and other compounds which are identified over the next few years for elimination from the marine environment, in line with recent agreements by North Sea countries (ENDS Report 282, pp 50-51 ). Air pollutants which might feature in the third list could include chlorinated solvents such as methylene chloride, tri- and tetrachloroethylene and 1,1,1-trichlorethane.
Still to be resolved are what should trigger reporting of releases of these substances to the PER. Criteria based on threshold pollutant loads or the toxicity of substances are used for this purpose in national water pollution inventories. But for emissions to air the qualifying criteria are generally the size or capacity of installations, while for waste it is generally a specified minimum quantity produced that triggers reporting.
Data comparability is another key issue. Reporting to most existing national PERs is based on a combination of direct measurement of releases - albeit at widely varying frequencies - and a range of estimation and calculation methods. Harmonising these practices will be essential if national reports to the European PER are to be comparable.
Confidentiality of data is another important issue. The report reveals that a minority of Member States are reluctant to see the identity of companies disclosed on the European PER, although this appears to be incompatible with EC rules on public access to environmental information.
Equally important, several Member States told the Swedish EPA that they will not be able to disclose economic data such as an installation's annual output or energy consumption or process yields because national legislation prohibits this. If this view prevails, it will be more difficult to use the data in the PER to make meaningful comparisons of, say, environmental performance within sectors or of the national rules applied to industries regulated under IPPC. This may find favour with some industries and Member States, but it would limit the PER's potential in promoting environmental improvement.