Technical University of Denmark. Risø DTU. RIMPUFF is an operational emergency response model in use for assisting emergency management organisations dealing with chemical, nuclear, biological and radiological (CBRN) releases to the atmosphere. RIMPUFF is in operation in several European national emergency centres for preparedness and prediction of nuclear accidental releases (RODOS, EURANOS, ARGOS), chemical gas releases (ARGOS), and serves also as a decision support tool during active combatting of airborne transmission of various biological infections, including e.g. Foot-and Mouth Disease outbreaks. DEFRA Foot and Mouth Disease. SAFE AIR II (Italy) – The simulation of air pollution from emissions II (SAFE AIR II) was developed at the Department of Physics, University of Genoa, Italy to simulate the dispersion of air pollutants above complex terrain at local and regional scales. It can handle point, line, area and volume sources and continuous plumes as well as puffs. It includes first-order chemical reactions and plume depletion by wet and dry deposition, but it does not include any photochemistry. SEVEX (Belgium) – The Seveso expert model simulates the accidental release of toxic and/or flammable material over flat or complex terrain from multiple pipe and vessel sources or from evaporation of volatile liquid spill pools. The accidental releases may be continuous, transient or catastrophic. The integrated model can handle denser-than-air gases as well as neutral gases (i.e., neither denser than or lighter than air). It does not include handling of multi-component material, nor does it provide for chemical transformation of the releases. The model's name is derived from the major disaster caused by the accidental release of highly toxic gases that occurred in Seveso, Italy in 1976. SPRAY (Italy, France) – A Lagrangian particle dispersion model (LPDM) which simulates the transport, dispersion and deposition of pollutants emitted from sources of different kind over complex terrain and with the presence of obstacles. The model easily takes into account complex situations, such as the presence of breeze cycles, strong meteorological inhomogeneities and non-stationary, low wind calm conditions and recirculations. Simulations can cover area ranging from very local (less than one kilometer) to regional (hundreds of kilometres) scales. Plume rise of hot emission from stack is taken into account using a Briggs formulation. Algorithms for particle-oriented dry/wet deposition processes and for considering the gravitational settling are present. Dry deposition can be computed on ground and also on ceil/roof and on lateral faces of obstacles. Dispersion under generalized geometries like