What should be the first action when using a fire extinguisher according to the PASS method?

The first action when using a fire extinguisher according to the PASS method is to pull the safety pin. This step is crucial because the safety pin prevents accidental discharge of the extinguisher. By removing the pin, you unlock the extinguisher, allowing you to use it effectively in an emergency. This step ensures that when you move on to the next actions—aiming at the fire, squeezing the handle to release the extinguishing agent, and sweeping side to side to cover the area—you're properly prepared for safe and effective usage of the extinguisher.