What occurs if air is unintentionally drawn back into a building due to a smoke ejector being incompletely sealed?

When a smoke ejector is incompletely sealed and unintentionally draws air back into the building, it leads to recirculation. This phenomenon occurs because the smoke ejector's operation creates a negative pressure that can draw in smoke and air from other areas of the structure rather than solely removing smoke.

Recirculation can be hazardous as it not only brings in potentially toxic smoke back into areas where personnel might be operating, but it can also compromise the effectiveness of the ventilation efforts. The concern with recirculation is that it can increase the level of smoke and heat in the environment, making conditions more dangerous for both firefighters and any potential victims inside the building.

In contrast, secondary convection refers to the movement of smoke and gases caused by differences in temperature and pressure. Paradoxical ventilation is a term used to describe the unintended movement of smoke and gases due to pressure changes that counteract the intended direction of airflow. Churning describes a turbulent mixing of gases and smoke but does not specifically refer to the issue of inadvertently pulling air back into a space.

Thus, recirculation accurately describes the phenomenon that occurs when incomplete sealing allows air to be drawn back into a building due to the actions of a smoke ejector.