Dispersion calculations with numerical simulation models or physical models (wind tunnel) are important devices in immission control related authorization procedures as well as in urban and regional planning processes.

In authorization procedures for facilities it is necessary to prove by means of dispersion calculations according to TA Luft that the project will not have any negative effects on the environment through air pollution. If a facility is not subject to the formal authorization procedures its effects on environment have still to be assessed by the directives of TA Luft.

In the planning period for facilities pollutant or odour dispersion calculations give information about the expected change in immissions due to altered emissions. But even if the intended construction will not cause any additional emissions the air quality can deteriorate, e.g. as a consequence of limited ventilation. Through a combination of flow and dispersion calculations it is possible to estimate a priori how the wind fields in the area are will be effected and what that means for the actual pollutant concentrations.

Dispersion calculations also enable us to assess the current state of air pollution and determine the percentage which certain single emitters are responsible for. Reasons for high contamination can be analyzed through suitable model calculations. Intended political measures to improve the air quality can be evaluated as to their efficiency and subsequently priorities can be set.