Some vegetation has well-defined chemical thresholds for damage. These have been used to compute critical loads for particular soil-vegetation systems. A similar approach, but using effects on fish or other aquatic animals, has been used for freshwaters. The maps show the amount of acidity which can be tolerated in different regions. Here we might expect to find damage from acidification.
Damage is most likely where the critical loads are small and the excess deposition is high.
Although deposition resulting from ammonia emissions can acidify, its contribution to acidification is uncertain and will vary from place to place. Across Europe, measurements of acid deposition show where pollution exceeds critical loads. However, these on their own do not identify who is to blame for any damage. Modelling acid deposition Computer models are used to quantify the movement of pollutants between areas of Europe. These simulate the emission, transport, chemical changes and deposition of pollutants throughout Europe.