Lakes Environmental Software has announced the acquisition of the CALPUFF atmospheric dispersion modelling system from Exponent. This transaction, confirmed on 5 May 2024, marks another step in the evolution of CALPUFF, a model widely used by researchers, environmental consultants, and regulatory agencies globally.

    CALPUFF is a US EPA Guideline model for all applications > 50km, it is also the guideline model for all near-field applications where the steady state assumption does not apply, i.e., complex terrain and complex meteorological environments (Sea breeze, boundary layers, etc.). In addition, it is a model widely used in odour modelling. The code of this model, while being publicized as "freely available," is not open source, as far as we know. Over the years, the ownership of the code has changed from SRC to TRC, Earth Tech, Exponent, and now Weblakes.