How do temperature extremes negatively affect the materials in a safety helmet?

Temperature extremes can significantly impact the materials used in safety helmets, leading to a reduction in their effectiveness. When exposed to extreme heat or cold, materials such as plastics, foams, and composites can undergo physical changes. High temperatures can cause materials to soften, distort, or melt, while extreme cold can make some materials brittle, resulting in cracks or breaks under stress. Both scenarios lead to a loss of crucial protective properties that helmets are designed to provide. This degradation can compromise the safety function of the helmet, making it less effective in protecting the wearer during an impact or other hazards. Thus, the correct answer highlights a vital concern in the maintenance and use of safety helmets in environments with variable temperatures.