This document will examine the technical, safety and administrative problems related to the use of flammable blowing agents in the production of extruded polystyrene boards (XPS). The document focuses on production of XPS rather than the design and certification of the XPS boards itself. The explanations, descriptions and examples are specifically focused on safety elements required for a proper production. The producer of XPS should always be aware of the product quality and on the basis of this knowledge eventually increase the safety system. The industrial use of flammable blowing agents, throughout the document also named gas, within the European Union (EU) is regulated by two directives approved by each member state.