Complex sentence: Positive pressure ventilation (PPV) consists of using a fan to create excess pressure in a part of the building; this pressure will push the smoke and the heat out of the building, and thus secure the rescue and fire fighting operations.
Split into simpler sentences: Positive pressure ventilation (PPV) consists of using a fan to create excess pressure in a part of the building. This pressure pushes the smoke and heat out of the building, and thus facilitates rescue and fire fighting operations.