Which undesirable effect can occur if windows on the upwind side are opened first in a horizontal ventilation situation?

In a horizontal ventilation scenario, the timing and sequence of opening windows are critical for effective smoke and heat removal while minimizing fire spread. Opening windows on the upwind side first can inadvertently allow the fire to be pushed or forced into uninvolved areas of the structure. This happens because the resulting airflow can create a pressure differential that encourages both smoke and flames to move toward areas that are not yet involved in the fire.

By opening the upwind windows, firefighters might unintentionally create a pathway for the fire's flow towards other areas, facilitating its expansion rather than controlling it. This is particularly important in larger structures where fire can rapidly spread if not managed properly. In such scenarios, coordinated ventilation efforts are key to managing fire behavior and ensuring the safety of both firefighters and occupants. Understanding this dynamic is crucial for effective incident management.