What does the term 'backdraft' refer to in ventilation systems?

The term 'backdraft' in ventilation systems specifically refers to the unintended flow of smoke into living areas, often occurring during a fire scenario. This happens when negative pressure builds up in a structure due to the consumption of oxygen by the fire, which can create a dangerous situation. When doors or windows are opened, or when certain ventilation changes occur, the previously trapped smoke and gases can be pulled back into the room, exposing occupants to toxic fumes and increasing the risk of injury or fatality. Understanding this concept is crucial for ensuring proper ventilation strategies are in place and for the safety measures during fire incidents.