In the P.A.S.S. method, which stands for Pull, Aim, Squeeze, and Sweep, the focus should be on aiming at the base of the fire. This is crucial because fires require fuel, heat, and oxygen to burn. Aiming at the base targets the source of the flames, where the combustible materials are located, rather than the flames themselves, which are already burning. Hitting the base effectively disrupts the fire's ability to sustain itself, promoting a quicker extinguishing effect.
Choosing to aim at the flames means you are applying the extinguisher material to an area that might not immediately impact the combustion process. Aiming at an exit or the smoke does not tackle the fire directly, which would allow it to continue burning and possibly spread. Therefore, aiming for the base of the fire is the most effective strategy in properly using a fire extinguisher based on the P.A.S.S. approach.