Smoke exhaust ductwork, in Europe, is typically protected via passive fire protection means, subject to fire testing (typically to NBN EN 1366-8) and listing and approval use and compliance. It is used to remove smoke from buildings, ships or offshore structures to enable emergency evacuation as well as improved firefighting. In North America, fireproofed ductwork may be used for the purpose of smoke exhaust, but it is more common to use unfireproofed return air ductwork, whereby no fire testing or listings are employed to qualify the ductwork for this use. Means of construction Smoke exhaust can be built using: ordinary sheet metal with external fireproofing treatment; or a proprietary duct that is inherently fire-resistant; or Fire resistant materials, such as calcium silicate. Gallery See also Passive fire protection Pressurisation ductwork Heat and smoke vent Grease duct Calcium silicate Fireproofing Firestop HVAC Listing and approval use and compliance Smoke Fire Emergency evacuation External links Smoke Extraction in Buildings Slide Show by Vysakh Manohar ISO6944 - 2008 Fire containment -- Elements of building construction -- Part 1: Ventilation ducts "Wisegeek" page on return air ductwork. Return air ductwork can be co-opted for cold smoke exhaust in North America Passive fire protection Heating, ventilation, and air conditioning