Typically, PPPs are different from exchange rates as the latter reflects not only the relative prices of consumption goods but a host of other factors, including international movements of capital, interest rate differentials and government interventions. As a consequence, exchange rates exhibit much greater variations over time than PPPs. Assessment of the Availability of Data from International and National Sources Data on private and public sector investments and current costs of air pollution abatement are needed to compile the indicator. Thus, for most OECD countries, reasonably harmonised expenditure data are available on a regular basis. In other countries, some expenditure data can be obtained from national reports or pilot studies.
Few countries are able to distinguish between national and local government abatement expenditure.
Pollution Abatement and Control Expenditure in OECD Countries. OECD Environment Monographs No. 75, Paris, 1993. The OECD questionnaire on pollution abatement and control expenditure and the underlying definitions have been approved by the OECD Group on Economic and Environmental Policy Integration.