In a one-person rescue, what is the first thing you should check before beginning CPR?

The first thing to check in a one-person rescue before beginning CPR is the safety of the scene. Ensuring your safety and the safety of the victim is paramount. If the environment is hazardous—such as in the case of fire, traffic, or electrical dangers—attempting to provide aid could result in further injury to yourself or the victim.

Prioritizing scene safety allows the rescuer to act effectively without putting themselves in harm's way. Once safety is confirmed, the rescuer can then assess the victim's responsiveness, breathing, and position as part of the next steps in providing care.