What is the first step in positive pressure ventilation?

The first step in positive pressure ventilation is to close up the house. This action creates an enclosed environment where the pressure difference can be effectively managed. By sealing off windows, doors, and other openings, the positive pressure created by the ventilation system can push air into the structure. This process is essential for ensuring that the air supplied by fans or blowers effectively forces stale or contaminated air out through designated exhaust points, enhancing indoor air quality or aiding in firefighting operations.

In the context of fire or smoke control, closing up the house helps to contain the smoke and heat while allowing the flow of fresh air to displace it. It is crucial to establish this closed environment before proceeding with the activation of fans for positive pressure ventilation to maximize its efficacy. Other steps, such as turning off the HVAC system or opening doors and windows, may come later but are not the first critical actions for initiating positive pressure ventilation.