Spridning Luft is part of the program suite MSB RIB, which is developed and used by the Swedish Civil Contingencies Agency (MSB). The main purpose of Spridning Luft is calculating and simulating emissions and dispersion of hazardous gases. In 2019, the project Improved dispersion modelling for first responders was initiated, with the goal to further develop the software by improving the capability to handle threats in an even broader scale by including more functionalities, such as new models handling sources for compressed gas, dispersion of chemical warfare agents and deposition over land and water. Through the project support for scenarios of flammable gases and explosions was also added. This report serves as explaining documentation for the new models and their applications.