Which type of ventilation occurs when clean air is blown into a structure to force fire gases out?

Positive pressure ventilation is a firefighting technique in which clean, pressurized air is introduced into a structure, creating a higher pressure inside compared to the outside environment. This airflow forces smoke, heat, and toxic gases out of openings, such as windows and doors. The primary goal is to improve visibility for firefighters and facilitate safer and more effective firefighting operations.

This method utilizes fans or blowers to generate the pressurized airflow. The effectiveness of positive pressure ventilation relies on the ability to create significant pressure differentials that push the hot, smoke-laden air out while allowing fresh air to replace it.

In contrast, outside-in ventilation typically refers to creating openings from the exterior to allow smoke and heat to escape, which is more about passive airflow rather than actively pushing air. Cyclic replacement involves cycling through clean and contaminated air without the same deliberate pressure application. First in, first out is primarily a logistic or inventory management principle rather than a ventilation method. Understanding the nuances of these terms and their application is crucial for effective fireground operations and safety.