What should be applied to a passenger to help them cool down during heat stroke?

Using cold wet towels is an effective method to help cool down a passenger experiencing heat stroke. The application of cold, wet towels to areas of the body where blood vessels are close to the surface, such as the neck, armpits, and groin, can significantly aid in lowering body temperature. This technique is beneficial because it promotes better heat dissipation and allows the body's thermal regulation mechanisms to function more effectively.

In the context of heat stroke, the goal is to quickly reduce the body temperature to prevent further physiological damage. Cold wet towels provide immediate cooling relief and can be easily administered in a variety of situations, making this approach practical and accessible for a flight attendant in an emergency scenario.