How long should each rescue breath be delivered to ensure effectiveness?

Each rescue breath should be delivered over a duration of 1 second to be effective. This timing is crucial because it allows for sufficient inflation of the lungs without causing overdistention, which could lead to complications such as increased intrathoracic pressure or air entering the stomach. Delivering the breath too quickly may not allow enough time for proper chest rise, indicating that the air is being effectively ventilated into the lungs.

In order to ensure the breaths are effective, rescuers should also observe for visible chest rise with each breath, as this is a sign that the air is reaching the lungs. Delivering the breath over 1 second creates a balance that maximizes oxygen delivery while minimizing the risk of negative outcomes.