Number 5.5 and Annex 2 of TA Luft (2021) specify calculation methods for determining stack heights and for dispersion calculations. The calculation programs BESTAL (Besmin, Besmax) and AUSTAL are exemplary implementations of these specifications. They are provided free of charge by the Federal Environment Agency.


The programs Besmin and Besmax (BESTAL for short) were developed for determining stack heights in accordance with Number 5.5 of TA Luft (2021). The program AUSTAL (starting with version 3) refers to Annex 2 of TA Luft (2021) and is the successor to the program AUSTAL2000 (ending with version 2), which refers to TA Luft (2002).

The explanations in Number 5.5 and Annex 2 of TA Luft (2021) already allow the calculation methods to be implemented on their own. With BESTAL and AUSTAL, the Federal Environment Agency provides public reference solutions. They can be used both for practical applications and for checking other programs that are considered to be capable of implementing the calculation methods in accordance with Number 5.5 or Annex 2 of TA Luft (2021).

Current program versions:

  • BESTAL 1.1.0, contains Besmin 1.1.0 and Besmax 1.1.0 (23.03.2024)
  • AUSTAL 3.3.0 (22.03.2024)

User hotline (for technical questions or problems):

  • See contact on the right hand side
  • Would you like to be included in the newsletter (notification of changes and updates via e-mail)? Send a short e-mail to the user hotline.

Last modified:

  • Problem 2024-04-02 (Besmin in batch mode)
  • 2024-03-26 BESTAL 1.1.0
  • 2024-03-26 AUSTAL 3.3.0
  • 2024-03-26 FAQ A16
  • 2024-03-26 Comprehensive update of the English pages
  • 2023-08-01 AUSTAL Patch 3.2.1


On the introduction of AUSTAL in 2021

The dispersion program AUSTAL (starting with version 3) is the reference implementation to Annex 2 of the TA Luft draft 2020. The program will be the successor of AUSTAL2000 (ending with version 2), the reference implementation to Annex 3 of the TA Luft 2002. AUSTAL and AUSTAL2000 were developed on behalf of the Federal Environment Agency (UFOPLAN projects 3714 43 204 0 and 200 43 256).

September 2021, Federal Environment Agency

On the introduction of AUSTAL2000, October 1, 2002

The TA Luft (Technical Instruction on Air Quality Control) has been amended in view of available advanced techniques and European Directives. The new TA Luft has been published on July 30, 2002 (Gemeinsames Ministerialblatt) and thus comes into force October 1, 2002.

Annex 3 of the new TA Luft specifies a Lagrangian particle model according to guideline VDI 3945 Part 3 (example implementation: IBJparticle) to be applied for dispersion calculations. In course of updating Annex 3, the computer program AUSTAL2000 has been developed as an example implementation of Annex 3, together with a documentation of its setup and application in the context of the new TA Luft (UFOPLAN project 200 43 256, "development of a model-based assessment system for regulatory environmental protection", Janicke Consulting on behalf of the German Environment Agency, UBA).

The program package AUSTAL2000 is a tool for applying the algorithms of Annex 3 of the new TA Luft in practice. The UBA has provided it to the public already in its draft version. This is to be seen as a service that aims for quality assurance and harmonization in connection with the dispersion calculation from the very beginning. The statements of Annex 3 themself are already sufficient for a program implementation of the described algorithms. AUSTAL2000 provides a reference implementation against which other programs, that claim to implement the algorithms of Annex 3, can be checked.

September 30, 2002, Federal Environment Agency

The history of AUSTAL2000 started almost exactly 21 years ago. At the NATO CCMS conference in San Francisco, which took place end of August 1981, I had just presented my formulation of Lagrangian modelling in inhomogeneous turbulence, parallel to similar works by Wilson and Legg & Raupach; in doing so, I delivered a promise made to Hanna during a conference in the preceding year in Amsterdam. The preparations for the TA Luft 1983 had not yet finished, nevertheless the participants already discussed how the TA Luft should develop on an intermediate and long-term time scale.

After the conference, we therefore sat together in the small village Kirkwood, in the mountains east from Jackson, in order to bring our ideas together (in the framework of the UBA project "handbook for immission calculations"). We, that was: Werner Klug, Paul Lühring, Rainer Stern, Robert Yamartino, and myself. Key points for a long-term concept that should reach about 5 to 7 years into the future were, among others:

  • Abandonment of meteorological statistics in favour of the simulation of individual situations in form of a time series.
  • Abandonment of classifications in favour of continuous meteorological parameters (e.g. the Monin-Obukhov length).
  • Replacement of the Gaussian model by a Lagrangian model.
  • Provision for topographical effects.
  • Modelling of NO/NO2 conversion.
  • Improved modelling of the dispersion and deposition of dust.

Now, after 21 years, major points of that former concept have been realised with the new TA Luft that comes into force tomorrow, October 1, 2002. Maybe one should meet again in the mountains and discuss how the dispersion model of the TA Luft should develop over the next 20 years.

September 30, 2002, Lutz Janicke

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