Critical loads studies (critical load is ‘a quantitative estimate of an exposure to one or more pollutants below which no harmful effects may occur’) have been used as the basis for assessing European strategies for reduction of sulphur emissions within the United Nations (UN) Economic Commission for Europe (ECE) Convention on Long-Range Transboundary Air Pollution (LRTAP). It is expected that the critical loads method will be applied to future international agreements under the Convention. Mapping of European critical loads conducted for the LRTAP Convention have progressed notably in recent years.

The concept of designing pollution control measures with the aim of protecting the most sensitive ecosystems, led to the creation of the Task Force on Mapping and Coordination Centre for Effects to implement these concepts on a European scale together with the corresponding National Focal Centres. The Russian National Focal Centre is used to illustrate how critical load data can be applied at the scale of a large country.

The policy implications resulting from the methods described in this review would support the development of an acidification protocol. While this has been suggested in the past, it is only now that scientific knowledge has advanced sufficiently to consider the feasibility of such a policy.