Large-scale chemical incidents and environmental emergencies occur infrequently, however when they do, they can have a significant impact on individuals and local communities. Provision of strategic, technical and scientific advice is key to the multi-agency risk assessment, risk management and risk communication during such events. This chapter explores: types of environmental emergencies and their impact on environmental compartments (air, water and land) that may lead to public exposure to chemical pollutants e.g. spills, fires, explosions etc.; principles of emergency preparedness and planning, including identifying key hazards and assessing potential to reduce the impact of environmental emergencies e.g. Seveso; ensuring roles and responsibilities are clearly understood and policies are in place to manage incidents, especially for cross-border health threats, and information sources and development of evidence-based scientific advice; the principles of emergency response, including environmental public health risk assessment methodology (source-pathway-receptor) and risk communication during emergencies; and a case study on fire.