Which action is important before opening a vent in a structure?

Determining the wind direction is crucial before opening a vent in a structure. Properly assessing the wind direction helps firefighters understand how smoke and heat will travel within the building and to the exterior. If the wind is blowing towards the vent that is being opened, it could potentially push smoke and heat further into the structure, complicating the firefighting efforts and increasing the danger to occupants and firefighters.

Knowing the wind direction allows firefighters to make informed decisions on how to ventilate effectively while minimizing the risk of fire behavior changes that can occur due to ventilation openings. This strategic approach is essential for maintaining a safe and effective firefighting operation.