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.

Hydrological zoning (or simply zoning) is an approach to divide land into different zones based on their hydrological properties. Typically, each type of zone has different land use and development regulations linked to it. This land and water management method aims to protect local water sources from risks of over-abstraction, land salinization, groundwater pollution and waterlogging by managing land use activities based on the assigned hydrological zones.  For example, zones with a high groundwater table, large amounts of surface water (e.g.