Smoke is recognized as the major killer in building fires, and smoke control systems can provide significant protection from smoke. The physical mechanisms that can be used to control smoke in a building fire are compartmentation, pressurization, dilution, airflow, and buoyancy. A smoke control system is an engineered system that includes any or all of these mechanisms to modify smoke movement. The primary purpose of smoke control systems is to maintain tenable environment in means of egress. Smoke control systems can also reduce smoke movement beyond the fire area, provide conditions to help fire service, reduce property damage, and aid in post-fire smoke removal.