Which safety measure is essential when storing full medical gas cylinders?

Securing full medical gas cylinders to prevent falling is essential because these cylinders are heavy and can pose significant safety hazards if they're not stable. A falling cylinder can injure personnel, damage the cylinder itself, and potentially lead to the hazardous release of gas. This precaution helps maintain a safe working environment, preventing accidents and ensuring that the cylinders remain in good condition for use.

In contrast, storing cylinders in direct sunlight or near heat sources can increase the internal pressure and risk of rupture, while keeping them in the same area as chemicals can lead to dangerous reactions or increased flammability. Thus, proper storage practices, including securing cylinders, are crucial for maintaining safety in medical facilities.