The critical loads/levels approach to gaseous pollutant emission control

Area of Science:

• Environmental Science
• Ecology
• Atmospheric Chemistry

Background:

• Increasing pressure exists to control gaseous acidifying emissions due to harmful environmental effects.
• Governments seek scientific methods for assessing emission impacts and planning controls, moving beyond uniform percentage reductions.
• The critical loads/levels concept is emerging as a potential international solution.

Purpose of the Study:

• To explore the critical loads/levels concept as a scientific basis for assessing and controlling acidifying emissions.
• To evaluate the adaptability of the critical loads/levels approach for various pollutants and environmental receptors.
• To present the target load/level as a practical extension for implementing emission control strategies.

Main Methods:

• Reviewing international developments in defining and quantifying critical loads and levels.
• Assessing the adaptability of the concept for different pollutants and environmental receptors.
• Examining the agreement on calculated critical load figures across various estimation methods.

Main Results:

• The critical loads/levels concept shows adaptability for diverse pollutants and environmental receptors.
• Despite varied definitions, broad agreement exists on critical load estimates calculated by different methods.
• The target load/level concept offers a practical extension for control strategy implementation.

Conclusions:

• The critical loads/levels concept provides a scientifically sound and internationally acceptable basis for managing acidifying emissions.
• The adaptability and broad agreement on critical load estimates support its use in environmental protection.
• Target loads/levels offer a pragmatic approach to minimize or prevent environmental damage from emissions.