What is the first step in the adult Basic Life Support (BLS) sequence?

The first step in the adult Basic Life Support (BLS) sequence is to ensure the safety of the scene. This is a critical initial action because it assesses whether the environment is safe for both the rescuer and the person who may require assistance. If the scene is not safe, attempting to provide aid could put the rescuer and the victim at further risk.

Before engaging in any emergency action, it's essential to evaluate the surroundings to identify any potential dangers, such as moving vehicles, fire, or other hazards. Once the scene is confirmed to be safe, rescuers can proceed with assessing the victim and initiating the appropriate BLS protocol, which includes checking for responsiveness, calling for emergency help, and beginning chest compressions if necessary. This foundational step ensures that subsequent actions are carried out effectively and without additional risk.