What should you ensure about a hard hat before using it?

Before using a hard hat, it is crucial to ensure that it has a metal shell without holes. This is because the primary function of a hard hat is to provide protection against falling objects and other impacts during construction or working environments. A metal shell signifies durability and the ability to withstand significant force. Holes or compromised integrity could greatly reduce its protective abilities, making the hard hat ineffective at safeguarding the wearer from potential hazards.

While comfort, weight, and design are relevant factors for user preference, they do not impact the hard hat's primary function of protecting the head from injury. The material and structure of the hard hat must meet safety standards to ensure maximum protection in hazardous environments.