Gas released from plants can have toxic, flammable or environmentally harmful effects even at very low concentrations. Releases can be fugitive emission, accidental loss of containment, continuous process relief, emergency relief or discharge of combustion products from engines. Prism quantifies and models gas releases from all causes to determine their impact on near and far filed sensitive receivers using 2D and 3D CFD software tools. The assessments compare the concentration of specified released gas component against COMPANY or industry recognised criteria, to determine their impacts. From the modelling, measures to prevent / mitigate impacts are proposed. For Greenhouse Gases emissions, Prism performs assessments in compliance with schemes such as the National Greenhouse and Energy Reporting (NGER).