What is a proper response if a diver is at risk of running out of air?

Using the buddy's alternate air source is the most appropriate response if a diver is at risk of running out of air. In a buddy system, divers are trained to share air in emergency situations to ensure both remain safe underwater. If a diver realizes they are low on air, they should prioritize maintaining a safe environment by accessing their buddy's alternate air source, which is specifically designed for such scenarios. This method allows both divers to safely ascend while avoiding the dangers associated with running out of air completely.

Other responses, such as swimming to the nearest boat or signaling for pickup, can take too long or may not be feasible if the diver is already low on air. A rapid ascent is extremely dangerous, as it increases the risk of decompression sickness and other serious complications. Therefore, utilizing a buddy’s alternate air source is the safest and most effective option to handle the situation.